Acquiring and retaining users requires two different things. Recruiting users: connect with groups. University students can use cash upon graduation, so selling still usable furnishings, clothes, decor, etc. will appeal to them. An accessible subset of university students is a sorority or fraternity. Connect with these organizations (undergrads make great brand ambassadors for this purpose in exchange for using your platform fee-free). You should take a transaction fee from each sale. Expand awareness of your platform via the sorority and fraternity regional and national chapters. As these early users age, their social networks change which creates user diversity. I specialize in identifying, developing and executing growth channels and I'm just a phone call away.