I love bitmixer.   I loved them a lot more when they didn't have minimum post counts and they simply paid based on activity (indicating that you have posted on the board but not forcing you to post to get paid).  In those days, their rates were understandably lower than folks who forced you to post.  But now that they've switched to the pay-per-post model I had to move on because their prices simply aren't competitive.  If you're going to do pay-per-post, you have to keep up with the market.  If you do pay-per-activity, then I think you can get away with a lower rate (honestly, I'd probably come back to bitmixer if they switched to pay-per-activity again).