$50 is tight alright, not sure. You ok with sideloading the hell out of something? I think you can get an Ouya in that range which is an earlier Tegra3 chip I believe, precursor to that Tegra that started in the shield handheld which is gimpier than the tablet/console.
I recall people buying those, gutting their garbage off it, and then slamming it full of emulators, KODI, XBMC, and other goodies and all in the size of basically of a rubiks cube.
Also piece of advice, whatever you get, loaded directly or side load it, get setup on google play AND amazon too. Under GP they have a really dumb but cool program of free surveys they do maybe once a week and then can be like a dime or a dollar or more, depends. But it's free money for clicking a few radio buttons or check boxes. I've bought quite a few games, apps, emulators for FREE using store credit.
Amazon isn't quite as challenging in that respect, they have a daily freebie. GP does too, but doesn't account it. I use an app called App Sales (looks red/white icon with a % on it) here's their website --
http://www.app-sales.net/ And they list all the paid, discounted, and 24+hour freebies of the day. Emulators I've seen rarely roll through there too.
Also the nvidia, yes the tegra ground up coded stuff can get into that PS3 level of quality being custom made, but overall the device still has such potent hardware within that it really can help across the board depending on what the app involved has as its system requirements. I've noticed quite a few emulators do code for Tegra to take advantage of that added overhead (like the Dolphin port.)