I have over 2 dozen cards. And alot of hardware that was bought haphazardly when I originally started. Like 5 750TX power supplies which was originally bought but then replaced with 1200 watt ones. Alot of extra 'others' sitting around as well. I never bothered to return them and just keeping them cause I'll find uses for them eventually. Including some good cases that was bought as well. UPS, a very good quality dell switch, KVM and some extra AC units... basically everything I needed for a data center install.
Everything (even the extras) all bought new from newegg. Been running for awhile and I've been running pure profit now. Everything I've bought has been paid for. So it's all just free money now. (Electric is free for me)
I don't even bother tweaking or overclocking my cards. Stability is rock for me. I've only had to touch the rigs once in the past 2 months. I was worried about Irene, but nothing. UPSes kept everything going strong all week long.
I know things can be improved easily. Lots of things I got are considered 'wasted' for bitcoins but I like toys. UPSs, KVM, smart switches were all a completely unnecessary expense but what the hell? I figured after everything is done I'll still have those left over which can easily be used elsewhere. Figured at the time I bought it, if I recouped my costs, then it's just free hardware. I calculated everything very conservatively at the time of purchase and figured it be great if I can break even. But to cross that line and now actually make money... GRAVY!