As a small business advertiser on Reddit, I feel as if this would be a good idea, especially for big businesses; however as I wrote before (http://news.ycombinator.com/threads?id=shoham), there are a couple of little things that I think you guys could be doing to be more business friendly with self serve ads for small businesses like my own: http://www.feed-forward.net
The three main ideas are: (1) lower the cost per day for ads (for a small business, with less than 100K a year in revenue, Reddit ads don't scale well). Facebook, and Google have a $1/day minimum. (2) Let the OPss of self serve ads moderate their post. It defeats the purpose of spending money on an ad, and having such an awesome idea such as the SSA program if the comments section is hounded by trolls, and moderated by no one. I've been told by admins that Reddit has a long history of free speech adherence, which is great, but posts are removed from subreddits all the time for not complying with the subreddits' rules, at the mods discretion. My proposition is that you guys extend this courtesy to buyers of SSAs.
Third, allow advertisers who have been advertising for a while to focus their impressions on people who have already clicked on their ads. Again, this is a small business-friendly idea -- I've focused most of my ad buys on r/music , a huge subreddit of 150K people. If after a month or two I could focus my buys on those users I've already engaged with in that r/, that would help bolster two objectives: keep the ad conversational, and help advertisers create a community around their submission/business. Once a few thousand people have seen my ad every day for two or three months, I can maybe even invite them to a sponsored r/...