It's really hard to beat Binghams when starting out since they've got everything you'll need (instructional materials, hardware for forms, and raw materials). In reality, a "kit" from Binghams is nothing more than the right laminations and glass needed to hit your desired weight when following one of their designs. It's the same materials as if you struck out on your own design. It's also the same cost as buying laminations if you're not making your own. The advantage of starting with a kit is that you will end up with a shootable bow very close to your desired draw weight if you follow their design. It's a great way to start and many glass bowyers started with Binghams - I did.
Another option is to contact Kenny McKenzie. I think he sells plans for his r/d bow design and can give you advice on lam thickness for this design. I don't think he sells the other necessary hardware for your form though. His laminations and quick customer service are better than Binghams.
A good book is Jack Harrison's "Traditional Bowyer: More Unnecessary Fun". He goes into a lot of detail on bow design and the physics of a bow. However, I don't think you need this book as the instructional materials from Binghams will get you what you really need to know. Also, there's plenty of good information on this form.
As far as cost, you'll probably have around $400 starting from scratch to turn out your first bow. This would be for your form, hot box, and raw materials (assuming you already have necessary tools).
Good luck and don't be affraid to ask question here.