download or print price

[gmcfuerte]

Hello
I have some photos to sell on my virtuemart.
i would like to set 3 different way to buy them
1)pay for download
2)pay for a 30 x 45 shipping
3)pay for a 50 x 75 shipping

Can i use a single custom field to do it?
witch one?
thanks for helping!
GMC