There is no marriage visa. The non immigrant O visa is used for marriage one year extensions of stay. So if you can obtain from Embassy that saves 2,000 baht and provides a 90 day entry and once here you just need to extend your stay before that 90 days expires (or 150 days if you obtain a 60 day extension to visit wife). Extensions cost 1,900 baht and for marriage will require 400k in your bank account for 2 months (so want to take care of that deposit soon after arrival).