Calculation Rules

[becq]

Dear all,

I did search through the topics regarding calculation rules / product creation in general but did not find anything suiting my needs. 

I am trying to create a product, which is bulk ware (pens) with logo printed. You can either buy the pens without the logo from a minimum amount of 1.500 at $ 1 / pc or you can choose to have your logo printed on the pens. The calculation based on that is a fixed amount for pre-print-services of $ 100 and then the cost each pen at $ 0.10. So manually I did the calculation on the basis of

pens 1500 (variable) * 1 = 1500
pre-printing charges (fix) = 100
printing 1500 (variable) * 0.10 = 150

sum = $ 1750

it would be awesome if anyone would be able to give me a hint of some sort to master this. the printing is not a prob at all as i just offer this as a selection drop down, but when the printing is selected, it has to include the pre printing charge automatically itself.

thanks heaps in advance!