My system which I just recently built to hold me over until I build something more monstrous:
☼ Phenom II x4 965 Black Edition = $130
☼ Cooler Master Hyper 212 Plus CPU Cooler = $35
☼ Foxconn Destroyer 780a SLi AM2+ = $100
☼ 2x1gb Kingston HyperX DDR2/1066 = $50
☼ Seagate Barracuda 320gb 7200.10 = $20
☼ Samsung SH-S223A 22x DVD+/-RW = $20
☼ Western Digital 1tb Caviar Green = $50
☼ XFX 650-watt XXX-Edition Modular PSU = $85
☼ Galaxy GeForce GT 240 1gb = $70
☼ EVGA GeForce 9600 GSO 768mb = $70ish (Got it for free though
☼ Antec Nine Hundred II Mid-Tower = $80ish
☼ Windows XP Professional SP3 = $35
☼ Logitech G15 Keyboard = $20
☼ HP S2031 20" LCD Monitor (1600x900) = $110
If my system is only worth the sum of it's parts ($875 not including what I would charge for labor), then that's all I would expect to get for it. However, I suffer no delusions, I could not get that much for it even though that's what the parts were priced at new. I can expect to reduce my system's worth by at least 30% due to it's being used.
As Adam Savage of the MythBusters would say (God love the MythBusters), "You can polish a poop, but that does not change what it is."
Harsh, but true. I quote your rig at: $450~525
(Including labor and Windows 7 Home Premium 64-Bit OEM, though not mentioned)
Fortunately, I do not plan to sell this rig, but use it for an extended folding beast even after I upgrade to a faster machine.
....even if it IS last-last gen tech.