My mac os x is currently 10.5.8. What is the cost to upgrade to the most current?

Question

My macbook pro os x is currently running 10.5.8. What is the cost to upgrade to the most current?

Answer 1

Assuming you have the upgrade system requirements you would first purchase a Snow Leopard DVD and upgrade to Snow Leopard. Then you update Snow Leopard to 10.6.8 to gain access to the App Store where you would then purchase and download Lion. Costs are $29.00 for Snow Leopard and $30.00 for Lion.
Lion System Requirements
Mac computer with an Intel Core 2 Duo, Core i3, Core i5, Core i7, or Xeon processor
2GB of memory
OS X v10.6.6 or later (v10.6.8 recommended)
7GB of available space
Some features require an Apple ID; terms apply.
See the following as well:
How to Install OS X Updates Successfully
A. Repair the Hard Drive and Permissions:
Boot from your current OS X Installer disc. After the installer loads select your language and click on the Continue button. Then select Disk Utility from the Utilities menu. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list.  In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive.  If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer. Now restart normally. 
If DU reports errors it cannot fix, then you will need Disk Warrior (4.0 for Tiger) and/or TechTool Pro (4.5.2 for Tiger) to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.
B. Make a Bootable Backup Using Restore Option of Disk Utility:
Open Disk Utility from the Utilities folder.
Select the destination volume from the left side list.
Click on the Restore tab in the DU main window.
Check the box labeled Erase destination.
Select the destination volume from the left side list and drag it to the Destination entry field.
Select the source volume from the left side list and drag it to the Source entry field.
Double-check you got it right, then click on the Restore button.
Destination means the external backup drive. Source means the internal startup drive.
C. Important: Please read before installing:
If you have a FireWire hard drive connected, disconnect it before installing the update unless you will boot from this drive and install the update on it. Reconnect it and turn it back on after installation is complete and you've restarted.
You may experience unexpected results if you have installed third-party system software modifications, or if you have modified the operating system through other means. (This does not apply to normal application software installation.)
The installation process should not be interrupted. If a power outage or other interruption occurs during installation, use the standalone installer (see below) from Apple Downloads to update.  While the installation is in progress do not use the computer.
D. To upgrade:
Purchase the Snow Leopard Retail DVD.
Boot From The OS X Installer Disc:
Insert OS X Installer Disc into the optical drive.
Restart the computer.
Immediately after the chime press and hold down the "C" key.
Release the key when the spinning gear below the dark gray Apple logo appears.
Wait for installer to finish loading.
E. If updating:
Download and install update(s) 
Use Software Update, or
Download standalone updater(s).
Once you then purchase and download Lion from the App Store consider this before you actually install Lion:
Make Your Own Lion Installer
1. After downloading Lion you must first save the Install Mac OS X Lion application. After Lion downloads DO NOT click on the Install button. Go to your Applications folder and make a copy of the Lion installer. Move the copy into your Downloads folder. Now you can click on the Install button. You must do this because the installer deletes itself automatically when it finishes installing Lion.
2. Get a USB flash drive that is at least 8 GBs. Prep this flash drive as follows:
Open Disk Utility in your Utilities folder.
After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Note the SMART status of the drive in DU's status area.  If it does not say "Verified" then the drive is failing or has failed and will need replacing.  SMART info will not be reported  on external drives. Otherwise, click on the Partition tab in the DU main window.
Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, set the partition scheme to GUID then click on the OK button. Click on the Partition button and wait until the process has completed.
Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.
Set the format type to Mac OS Extended (Journaled.) Click on the Options button, check the button for Zero Data and click on OK to return to the Erase window.
Click on the Erase button. The format process can take up to several hours depending upon the drive size.
3. Locate the saved Lion installer in your Downloads folder. CTRL- or RIGHT-click on the installer and select Show Package Contents from the contextual menu. Double-click on the Contents folder to open it. Double-click on the SharedSupport folder. In this folder you will see a disc image named InstallESD.dmg.
4. Plug in your freshly prepared USB flash drive. You are going to clone the InstallESD.dmg disc image to the flash drive as follows:
Open Disk Utility.
Select the USB flash drive from the left side list.
Click on the Restore tab in the DU main window.
Check the box labeled Erase destination.
Select the USB flash drive volume from the left side list and drag it to the Destination entry field.
Drag the InstallESD.dmg disc image file into the Source entry field.
Double-check you got it right, then click on the Restore button.
When the clone is completed you have a fully bootable Lion installer that  you can use without having to re-download Lion.