I know this thread is asking about consoles, but this assumption it's based on is actually incorrect. You can build/buy a decent gaming PC that will run with the visual fidelity of these "next-gen" consoles at higher resolutions and framerates than they could achieve, pretty easily by the $400-500 mark. Heck, you can get video cards that will run better than the consoles can put out and put it in your existing PC in many cases, for $100-150. Here's an example at $165 minus 25 dollar rebate = $140 shipped: http://www.newegg.com/Product/Product.aspx?Item=14-127-728&Tpk=N82E16814127728 , which is a GTX 650 Ti Boost 2GB card (just shy of the plain GTX 660 thanks to the increased memory bus width).
If you wanted to build a computer around it, you could snap up a $100ish i3 Haswell CPU, a plain jane motherboard, 8GB of DDR3 for around $50-60, and a HDD ($70-80 for a 2TB one) or SSD (120GB on deals go for around $80 or less nowadays if you wait for a sale). Add in a decent case for $30-40 (and an optical drive if wanted for $15-20) and you'd be pretty much good to go from there simply using your current monitor, keyboard, mouse, speakers, etc. (which you already have if you're typing on this forum).
If you wanted to buy pre-built (or just don't build your own period) there are a lot of deals that vary in specs and quality of machine, but they can be found pretty regularly at deal forums like slickdeals or fatwallet with not much worse specs than those listed above, and definitely fast enough to outpace what the consoles will be putting out at their launches.