Monoprice Maker Select 3D Printer v2 is what I got. It was on sale for $250, or you can buy a refurbished one for $250 if you aren't willing to wait for a sale. This is the best printer you can buy for under $300; it has a heated bed, and its fully assembled. Also, there is a big community around this printer so it's easy to troubleshoot problems and you can find a ton of printable mods to improve it. I've had great results with Monoprice's customer support, so don't be afraid to get the refurb one.
You could also go for the Mini Select for $220, or $180 (refurbished). I would get the Maker Select, though, just for the bigger build area. Here is a link to the refurbished one https://www.monoprice.com/product?c_id=107&cp_id=10724&cs_id=1072403&p_id=21864&seq=1&format=2
Good luck! and if you need anything else just ask.
