Well, sure... cheapest option could be to fix it, but it sounds like he doesn't want to do that.
So... if you want to put a new machine together, this is the absolute cheapest:
CPU: $37.99
AMD Sempron LE-1250 Single Core Processor 2.2GHZ Socket AM2 512KB L2 Cache 45W Retail Box
http://www.newegg.ca/Product/Product...82E16819103189
Motherboard: $54.33
MSI K9N6PGM2-V AM2 GeForce 6100 NFORCE430 mATX DDR2 PCI-E16 PCI-E1 2XPCI SATA2 LAN Sound Motherboard
http://www.directcanada.com/products...anufacture=MSI
RAM: $14.99
Buffalo Select D2U800C-1G/BR 1GB 1X1GB PC2-6400 DDR2-800 CL5 240PIN DIMM Memory
http://www.ncix.com/products/index.p...o&promoid=1066
Hard Drive: $43.25
Western Digital Caviar SE 80GB SATA 7200RPM 8MB Cache 8.9MS Hard Drive
http://www.directcanada.com/products...acture=WESTERN DIGITAL
DVD Writer: $22.99
Samsung SH-S223F/BEBN 22X Speedplus DVD+-RW SATA DVD Writer OEM
http://www.ncix.com/products/index.p...1&promoid=1066
You can just order all of them through NCIX and do pricematch.
So that would come out to $173.55 plus tax, if you're reusing your existing computer chassis. If not, that would be another $40 or so...
Of course, I would highly recommend spending just a little more money to get the best value... spending $10-20 more for a dual-core CPU for sure... and you'd probably want a bigger hard drive for $10-20 more as well.