I agree with Wolf. I'm in the boat you are in. I have an Athlon II x4 640 that I'm going to try and sell. Unfortunately on ebay the going price looks to be about 40-50 at the upper end. My old board, I've got a dual core chip that will work in it, so that and my old ram I'm going to pop together into a case for my inlaws to replace their 10 year old hp.
I mean honestly, I sold my GTS 450 for 31 bucks. But hey money is money. Saving up for either a newer power supply or monitor.
My new system I just got(I went the opposite of what you did).
FX 8120 8 core(I know this is a bulldozer chip, but at least it's unlocked for overclocking, got it at Microcenter for 140 bucks which seemed like a good deal)
Gigabyte 970a-ud3 board
Gskill Ripjaws ddr3 1600 8 gb kit
Radeon 7850 2gb
250 gb Seagate hard drive(had it around, using as a boot drive until I get an SSD)
1 TB seagate used for storage(steam games mainly lol)
Ultra LSP 650 watt power supply(considered a weak unit by some, I've had it 3 years, 38 amps on the 12 volt rail, voltages are stable, but not gonna push it with overclocking till I get a better power supply).
CM Storm Scout case
V6 GT cooler seems to keep idle temps at close to 30 degrees celcius, hoping they go down as the arctic silver breaks in.