The Radeon 4850 512 and GTS 250 are roughly $100 dollars.
Of those choices, I'd lean towards the GTS 250.
Yep, If you want something like that, You might be able to get a GTS250 but typically there really $130 $120 but put in 20-30 Dollars, as this is card is a bang for the buck, also the 5770 is quite good, The GTS250 And 5770 are quite close in performance.
If you aren't gaming then any card will do really or just get a motherboard(or processor) with built-in video.
For gaming at 1920x1080 at least an HD5770 is recommended in general, preferably a GTX 460. However if you are willing to lower some settings and play the more intensive games on medium settings then something like this will be adequate; http://www.newegg.com/Product/Product.aspx?Item=N82E168...
It's a good deal. Get it while it's still that price if you aren't willing to raise the budget for an an HD5770.