Drupal user Rob Knight has begun work on a new module - http://drupal.org/project/pm - which aims to provide a market maker in Drupal.
A quick review of his TODO.txt shows a bit of work left (userpoints integration, in particular, is important).
The Market module I made purposefully relied on as many other modules as possible to reduce the amount of code that was being re-invented. However, it also made it a lot more fragile to rely on all of those which was ultimately where I became frustrated and stopped working on it.
Rob is mostly taking the opposite approach and has no dependencies at this point (userpoints will be the first one). I think in the long run that's a reasonable strategy to follow.