It's stupidly overpriced at this point considering how old the hardware is. We're talking about a used machine that's been in regular if not heavy use for over three years now. Anyone buying a PS3 today is better off getting a slim with completely brand-new, quieter, cooler, less power hungry, and sleeker hardware with hundreds and hundreds of GB of HDD space and whatever free pack-in game comes with it... for a cheaper price. Honestly you'd be an idiot otherwise.
Shortly after they stopped manufacturing them they were much more valuable. People were still regularly playing PS2 games, games like Persona 4 were still coming out, that MGS Trilogy collection was big, etc. Most importantly there was no PS3 slim model, they simply stripped out the BC so it wasn't like you were sacrificing your hardware just so you could have PS2 compatibility shoe-horned in. Plus, as we get closer and closer to PS4's release it's just not as important anymore. Eventually you'll replace your PS3 and either hope PS4 has BC with PS2 or pull out your PS2 again anyways.
I still use my phat PS3 but only because I bought it back years ago and don't want to pay money to upgrade. If it broke I'd definitely go with a slim though, the BC was useful but I have my slim PS2 in the closet anyways. If I didn't have the BC, plugging in my PS2 for the EXTREMELY rare occasions I actually ever want to play a game would be a cinch.