You should pick the cabinet style you wanna go with, and specify what hardware your planning on using… Dreamcast ? or Naomi ? Mame ?
Most American style cabinets are made from MDF and lumber, you can purchase plans from the Mame room guy, or use a model from Google sketch up, modify it for yourself and get measurements and work from there…
There are also “modern” japanese style cabinets like the Noir and Vewlix, both are awesome in my opinion. Donovan Myers site lists his costs and stuff.
Assuming you have a console and a tv, and a hackable controller and all you really need to do is build your cabinet, then your cost could be as low as 200.00 USD.
Donovan Myers - Vewlix cab (many people have copied this model and modified it for themselves)
PDF of Vewlix Tournament Edition Plans?|?Donovan Myers
American Style Cabinet
Depending on the hardware inside, you’ll need to look at various how to’s on this and other sites for pad hacking, Cthulhu, or Jamma harnesses.