Your comments and experience are very appreciated. As another user pointed this out too, we'll prepare a small example list to be easier to understand pricing.
We are practically focusing on quality but we are doing our best to keep costs low for everyone.
With vectors imported into a common data structure you just need to convert curves to line segments with enough segments to maintain a reasonable approximation and then add up their lengths. Cairo and Anti-grain geometry can do the heavy lifting for you there. Anti-grain has example code for doing this adaptively.
Either way, clearly you're already calculating this value for billing, no? Or are you just using laser run-time for the bill, and estimating that based on the user's guesstimated path length?
eMachineShop has offered a similar service for years.[1] But they offer a much wider range of services, and their one-off prices tend to be higher. This new service seems to be aimed more at non-functional decorative stuff.
[1] http://www.emachineshop.com/machine-shop/Laser-Cutting-Servi...
Edit: After a bunch of clicking around, I realized I have to initiate an order to figure that out. And I need to provide material, thickness, X*Y dimensions, path length, and a couple of extras to get to hopefully get an estimate.
My feedback: please give me some pricing examples early on. Make it prominent on the start page. Like photos of 2-3 objects, what they cost to make, and what their respective parameters are.