I still think it would be possible to work this out with a more creative ToS. Problem one could be managed by making it part of the ToS that you won't aggregate

I still think it would be possible to work this out with a more creative ToS. Problem one could be managed by making it part of the ToS that you won't aggregate from other sites. Problem two could be managed either by making it part of the ToS that you don't post your own listings, or by making you pay to have them listed at Craigslist at the same time.