What GPU should I pair with this build?

Is this setup actually worth it $800? I'm thinking about picking this up and then adding a GPU later on. My budget is capped at $250.

CPU: Intel Core i3 Haswell4150 3.5 GHz, 64bit
Motherboard: H81 MB, 64bit, LGA 1150 socket
RAM: 4GB DDRIII
Hard Drive: 500GB HDD
Case: Phoenix
Optical Drive: DVD-RW, dual Layer, SATA
PSU: 500W
Audio: 7.1 channel audio
Misc: PCI-express, SATAII, 3 PCI slots, 10/100MB LAN

It’s probably the power supply, since that MS unit is basically junk...

1 x FORTRON 400W Power Supply, HEXA Plus 400, 12cm fan
1 x DDR3 4GB (1x4GB) Crucial, 1600MHz CL11
1 x ASUS H81M-R, 1150, H81 express chipset, DDR3, 2 slots
1 x Intel Core i3-4150 (3.50GHz,512KB,3MB,54 W,1150) Box
1 x Zalman T5 mini tower case. 170(W) x 427(H) x 348(D)mm.
1 x TOSHIBA 500GB, 7200rpm, SATA 6 Gb/s, 32MB, DT01ACA050
+
1 x MSI R7 250X 1GD5, 1GB GDDR5 128GB, DVI + HDMI + Display Port

$1045 ADM