I ran across this infographic of the original price and the adjust for inflation price of a few notable video game consoles. I have no idea if these are correct, but it was on the internet. I can't imagine anyone would like on the internet.
The first thing that jumps out at me is how ridiculous expensive the Atari 2600 was, $200 in 1977 was no small amount. I think your best values on here are the Dreamcast (natch), Xbox 360 and the Wii. The 360 had a ridiculously long life span (assuming you never got the RROD) and revolutionized the way you play consoles on-line. The Wii and DC fizzled out relatively quickly but considering how revolutionary both were AND how relatively cheap they were I can't not consider them great values. You can take your pick between the 3DO and the Neo-Geo as to which is the worst value. Both consoles were ridiculously expensive and never had a great games library. For the cost of a single Neo-Geo you could buy a SNES and Genesis and a TurboGrafx 16. Being able to swap memory cards with arcade games isn't worth that kind of money.