No problem on the pricing, being an accountant I’m always willing to talk about money… 
There are a couple of good threads on what materials to use/not use in your machine.
Resources for tests on laser cutting various materials
Laser Made This thread is currently active and has an excellent link in it.
I’ll be sourcing my material from all over, depends on what type of material it is. As the Glowforge crew have found out material varies from batch to batch and supplier to supplier so by only using material I’ve sourced I’m hoping to mitigate the variance between the materials that go into my machine. This should also minimize playing with power and speed settings while I try to figure out how the material reacts.