$60 for a mattress
$9,900 for a used Volvo
$1 for a lazy, recently graduated roommate

This isn’t eBay or Craigslist. This is “Marketplace,” Facebook’s latest feature. The members-only social network, which is open to anyone but most popular with high schoolers, college students, and recent graduates, has created a sort of cyber flea market where users post their trash and treasures for sale. The site’s developers came up with the idea when they saw users posting items for sale in the Notes section of their Facebook profiles.

Users are having fun with the new feature and putting it to good use. A recent post on Marketplace seeks a “soul mate”—for free. There are also more than 300 posts about housing in Washington.

Sellers can block portions of their profile from interested buyers and can choose which networks of users see the listing. They can also see how many people have viewed the post and get basic information about interested buyers by clicking on their profiles. Potential buyers can message questions to sellers, who have the option of posting the answers in a FAQ section of their post.