@Ja**
Yepp, plus all the documents you submit must be written in Thai. You have to have a office with minimum 3 month lease term, and publish to the Royal Gazzet, so add a couple thousand baht along the way.
I tried doing it myself and got as far as the first meeting with at the MoC. I'd recommend you go that route and talk to the guy there, they are really helpful and friendly. Basically there are 2 pathways, you can do a sole proprietorship were you do business as yourself (can't get a visa or wp in the future) or you setup a limited company. Both have pros and cons. If you hire a law firm it will run you 55-75k baht for them to do it for you and honestly, I'd probably recommend that route if you want to setup a limited company. I can recommend a couple in Bangkok if you want.