Call around and see what most are wanting for a deposit. Then pick one you feel good about after looking at examples of finished projects from that shop. After you drop it off to get done, stop in if you are close enough each month and make a payment, or at least mail one every month.
Will have it most likely paid for by the time it is ready to go, and haven't had to lay ouy a big chunk all at once. Bonus is that if you stop by in person each month, shows that you are a serious customer who is wanting to hold up his end, and you get to check progress on your work at the same time, helps build a working relationship that benefits both of you on future projects.
Like it has been said, mounts take awhile to get done, you worked hard and it is your first, which is always a trophy and you don't want it looking bad or falling apart.
