While that might be a possibility, I highly doubt that's what's going on. OP said he PM'd this guy at least twice since the first time it happened months ago, and while the offender was active on this site, he never responded.
There's some perfect-world scenario where this guy is not up to...
Please don't wait too long. I know you probably don't want to be a dick, but at the very least, let us know who it is so we don't trade with him. If you need motivation, just think about how he doesn't give a shit that he's ripped you off.
So he did it again on July 2? Reveal who he is, so nobody here trades with him, leave a negative feedback on heatware if you have it, and MOST importantly, report the sale to Microsoft to try to get the account banned. He deserves no less.
Seriously, stop being nice.
Yes, they are registered. Here are the full details:
FORM FACTOR: 240-PIN DIMM
STORAGE CAPACITY: 4GB (1x4GB)
MEMORY TECHNOLOGY: DDR3 SDRAM
BUS SPEED: 1333MHZ DDR3-1333/PC3L-10600
DATA INTEGRITY CHECK: ECC
SIGNAL PROCESSING: REGISTERED
RANK FEATURES: DUAL RANK X8
CAS LATENCY TIMINGS: CL9...