Due to your $50 budget, as well as current pricing, I would with the following:
GIGABYTE GV-N220OC-1GI GeForce GT 220 1GB 128-bit DDR3 PCI Express 2.0 x16 HDCP Ready Video Card - Retail
DDR3 Memory + Overclocked at 720MHz
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125295
1. After the mail-in rebate, it will be $50.
2. On average, it is a tad bit faster than the ATI 4650 and a tad bit slower than the ATI 4670.
3. Support for DX 10.1.
4. DDR3 memory (versus DDR2/GDDR2)
5. Has a native HDMI out.
Disclaimer: I would have picked a 4650/4670 like many other users. However, for this price... and your upgrade plan... this card will probably be better for you. (And, since this card is "new tech," you may be able to resell it once you upgrade.)