For the price you're offering, you won't find any good programmers that'll work for you, you'll only find hacks who think they can and are more than willing to take your money while learning.
If you think you can spend 2k to have some monkey write some code for you that you're going to sell and make a ton of money with, you're sadly mistaken. If you think your idea is with 90% and he'll do all the work for 10% and 2k, you're also sadly mistaken and very like to be taken, as you clearly have.
If you think you have an idea that's worth anything, you need to find a good programmer and bring him on as a full partner, he'll be the one doing most of the work and offering anything less will be insulting and unlikely to work out for you. He needs to be as vested in the success of the endeavor as you or it'll likely fail.
If you just want your idea implemented by a contractor and you keep all ownership and a reasonable estimate is that it's two months of work, then you're looking at 10k to 15k to get it done right by a competent programmer, not 2k. You'll get what you pay for.
Having a one year project and having no source code for what you paid for is unreasonable for a key asset of your company.
Your best bet at this point is going to be to start over. Get yourself a good hacker; I bet there are a few around here looking for short-term gigs - I am, for one. If you have a decent written spec, it should be no problem for any decent programmer to give you a reasonably accurate timeline and meet the milestones. As others have said, pay by the milestone, and make sure you get the source code.
I imagine it's plausible given how easy most .NET projects are to disassemble. If you contact me at my email address at (alnayyir #at# gmail dot com) I could discuss the matter further with you.