Using two different calculation type for one condition in purchasing

Question

hi
purchasing price must be callculated as the mix of fixed and quantity calculation types, example is below;
for material A whose purchasing unit of measure is quantity (piece) but base unit of measure is gr.
1.from 1 gr to 500 gr discount must be 50 usd  as fixed,so 1 gr discount is the same with 499 gr discount.
2. from 501 gr up to x, 0,10 usd per gr
for example;
if quantity = 10 and  total default gr from material 450, discount must be 50 usd as fixed.
but during good receipt in migo 10 piece can be 600 gr so, price must be calculated as 600*0,10 = 60 usd.
or vice versa,in purchasing order total gram can be gretaer than the gr which will be used in migo during good receipt .
if quantity = 10 and  total default gr from material 600, discount must be 60 usd as scaled.
but during good receipt in migo 10 piece can be 450 gr so, price must be calculated as 50usd as fixed.
it s a little complicated.
Thanks in advance.

Answer 1

TW Typewriter
If the coding is not written correctly, it would definitely affect the system performance.  This is not only for user exit but also will be applicable to routines.  So it makes no difference. 
And is not difficult to get an access key to do this development
Not in all cases.  In some projects, getting an Access Key itself is very difficult and it undergoes cumbersome process from client side.  So we have to take a decision on case to case basis whether to go with routine or user exit.
G. Lakshmipathi