That's a major reason for craigslist's success but not the only reason. Clearly another is network effects. Given that, I wonder whether targeting the largest s

That's a major reason for craigslist's success but not the only reason. Clearly another is network effects. Given that, I wonder whether targeting the largest sales category is a good plan for a competitor -- surely it has to do with your goals, resources, etc., but imho it's worth considering that the best opportunity may be in the categories where craigslist facilitates the fewest sales.