A while ago I bought a non-working late 2009 Mac Mini for £68 including delivery, thinking that the problem would probably be something like the hard disk that I could fix or replace. Instead it was completely DOA, with some sort of motherboard fault I couldn't locate or fix. I managed to establish that it wasn't the power supply, which was OK with my previous Mac Mini, and tested the hard drive and found that was OK too. I'm pretty sure that the DVD drive is also OK since it lived on the same daughterboard, and the motherboard shows no signs of making a recovery if they're removed.
I thought about trying to get it fixed, but even a quick look at repair prices told me it would probably be a non-starter, so eventually I decided to do a bit of asset stripping.
So far I've sold the power supply for £25, the hard drive for £20, and just auctioned the rest of it (less the DVD drive, which is still on sale - full refund offered if DOA) for £34, all plus postage. So I'm currently eleven pounds ahead, which isn't too bad. Must admit I would have preferred to have had the working computer, but it's better than nothing.