I run a site called http://www.sportspeech.com I am going to cut straight to the chase, my site has 6,636 members with 721 active members I am selling about 100 signature spaces on this site from 100 members (obviously some are worth more than others). I can make more posts happen from each user, depending on how many user signatures you would like to buy. My prices: 10 posts a week from a user- $1 a month of signature space 20 posts a week from a user- $1.80 a month of signature space 50 posts a week from a user- $4 a month of signature space You can ask for up to 100 users altogether (as this is the maximum I can get to post).
Brilliant service which I have used before and will definately use again. Posts are of excellent quality and it has helped my traffic increase.