Hi.
Personally speaking, I think you can over think somethings too much.
For example, I have 2 prices for printed banners, white background and when the printer changes the background to another colour,
You could have a price for a banner printed with 20% ink coverage, then 25%, then 30% and so on and so on. You would end up with 20 pages just for printed banners.
This would cause the customer to be hanging on while you work out which category his design falls into.
Keep it simple as you can.