You mean the small tanks with the filter system built in? If so, those things are typically trash...sorry to hear you got ripped off on Marketplace.

It's typically best sticking to base aquariums (when it comes to second hand purchases), even then you need to inspect the corners and everything to make sure there isn't much damage with the silicone seal.

Good luck with tank breeding if you do it! That definitely requires a lot of patience. I only tried it for a short while. I could never get my breeding tank to cycle correctly, so turned it into a turtle tank instead.