I spent a lot of time today on the Sculpteo site, uploading models, trying different configurations to optimize costs based upon their non-published pricing model. A couple of things became are very apparent. Grouped parts are much less costly than individual parts selected separately. And small individual parts are relatively expensive.
I uploaded a number of new complete mod models basically just differing on the the type of fire button (Ball vs Alp, High vs. Low). The pricing model for these type of set-up are much more favorable than shapeways. Thats the good news.

The bad news is that smaller parts like buttons and rings are 2-3x more costly. I havent uploaded all the individual part for customizing colors on the DNA v3.1, but I did upload the PeKo mechanical, both as a single model and as parts and I assume that the button/ring costs are going to be in the same ball park. Right now Sculpteo is not co-operating on additional uploads (I am getting a java code error...), but the site is live and you can check it out. White Plastic is uber cheap in grouped models. Much much less than Shapeways. Colors (including white) can come in unpolished or polished. The cost of these look slightly below Shapeway, Alumide is very inexpensive vs Shapesway...almost 30-40% cheaper.
The model I showed earlier is white plastic that was polished. After playing with it for a bit, I really like the polished effect on the internals. I used to only get plain White plastic, but the rougher edges always needed a little attention, the new parts just slide together.

So the combo of the white polished shell parts and the white polished internals along with a better price is really nice bonus, especially, if you are going to paint your mod.