I did get mine replaced... It was at least 2 weeks after I had paid for the initial units before he shipped anything to me, and that happened because I contacted him. The defective unit I had arrived with a Windows installation on it that was BSoDing on boot with a licence violation error. I ultimately determined it had defective RAM. After I shipped my defective unit back to him he claimed to have copied an operating system onto the flash drive (which I was able to do quite well, it was failing memtest86 over a large chunk of RAM) and he was going to resell it. He then tried to give me a story about how much money he was losing and wanted me to pay for more shipping after I had received my replacement... This process was a pain and ultimately took 8-10wks to resolve.
I don't recommend purchasing from him.
I saw the price and gambled. The DX model he was selling is nice, it's 586 based and very responsive with a nice wireless NIC. GX units are 486 based and have wireless NICs that really only support WEP encryption (see Thom's & Hari's posts earlier in this thread). I figured I could get 4 (could actually have got 7) from this guy, with charge cradles, for less than the price of 1 from lmcecompatible (@USD$459.98+tx with a charge cradle) and if only 1 worked...
If I was to do it again I'd probably go for an Archos 7 Home Tablet and use an Android Touch Orbiter.