To be honest, I'd be hesitant to recommend most "go-to" freelancer sites like oDesk, Freelancer.com, etc. There definitely are genuine skilled and hardworking people on these sites, it's just there are tens of thousands more that aren't.

I would:

- Look to see if any Visual Studio Extensions you [use/like/that are similar to what you have in mind]'s authors are easily tracked down and see if they'd be open to taking on your project.

- Look within your own network/circles for someone you know or trust.

- Google.

I'd much rather "headhunt" a freelancer and make up my own mind through seeing how they present themselves online, their past work, etc, without being constrained to a thrown-together proposal on a freelance site to decide.

Good luck!

I used ODesk, paid somebody $20 an hour for C# work.

Went ok. Guy was good enough.

Saves a lot of time for myself and was worth the $20 an hour.

I asked what your favorite C# language feature was and your favorite nuget package to screen candidates out. There was a HUGE difference between two tiers of answers. Either people completely punted or gave me insightful answers.

Will be doing more or less the same thing on Odesk in the near term future because it worked out ok enough to be worthwhile.

At a startup I consulted for, we had a developer who had come via toptal.com. He was heads and shoulders above anyone I've worked with via oDesk etc. Good screening could find diamonds in the rough, though.

You could also google around for people who have done what you want (built extensions you like) and ask them if they would consult on this project for you.

http://www.lancelist.com/ is a big list of alternatives to the larger sites.

Full disclosure: I am the author, so this is a plug!

I use oDesk. There are lots of talented humans there. I use a tool I made at http://ars.io to help filter the best 2 of 200

I am a freelancer myself. I use elance. I got paid but only after a month after the last deliverable. Not quite the employer's fault because he admittedly was new to the on-line site. If I have to point out a fault, the elance process needs to be improved.

If payment is not prompt, freelancers will pick other sites.