Just for comparison purposes, what do PC players see as a reasonable price for a good gaming PC? If it is significantly more than an Xbox or PS3, is the extra worth it?
That depends on how powerful you want it. It can be anything. If you wanted to play Skyrim, you could get something under $400 or cheaper based on where you are. If you already have a PC and you just wanted to upgrade, a graphics card and RAM would be even cheaper and that. Also if you go to an Indy PC Builder/Repair type shop they could make it a even cheaper and one even more Mega'ly powerful than one you would get by going into a Best Buy or something. You can even go in with a Video Game Box and say "I want a PC that Runs this!" and they could build one awesome for you. But thats just what I usually do.
I actually used to upgrade my PC just for TES games because they are usually so pumped up that if you can play them super fluidly you can play anything for years on it. I did exactly as I discribed at a local guys shop here where I live. I brought the Morrowind Stats on a Piece of Paper before it came out and said "I need a PC that will Play this!", and he made me a Super Awesome PC that blew my mind out playing it. Then when Oblivion came out, I actually brought him My PC and the Spec's for the Game and said, "I need this PC to Run these stats".
He would ask how much would I like to spend on it, as well ask "Do you want it to run game well, or do you want it to run it so good it melts your brain?"
I would always say "Brain-Melting Mode please"