Ive had one S3+ where a PCI-e connector started to turn brown with very mild over-clocking. So I changed the clocking and switched to the other PCI-e connector that was still good (on that side). Once I saw that I decided to under-clock all of my S3+s from there on out to maintain resale value.
Thanks goodness by then the S5 had come out and I started switching over and selling all my S3s on eBay. Im running all of my S5s at the stock clock rates and have not had any problems.
You should be able to get a used S3 on eBay for the $75 to $100 range?