On Friday I gave http://www.trymyui.com a go - they offer one free usability test if you register and then it's around $40 per test after that. Within 2 hours of signing up I got an email saying my usability test was ready - it was an 8 minute screen capture with audio of somebody using my website, trying to accomplish the task I gave them.
I really recommend you give this a go, and if you can afford it, pay for some tests on your sites to see what you can do to improve usability. Good, user-friendly sites are what drives conversion, gets people talking and sharing your stuff. Give it a go!
I have no affiliation with trymyui.com