A few months ago I purchased a fat used PS2 from GameStop.com. What I received was a "frankenstein" PS2: a SCPH-5xxxx board placed in a SCPH-3xxxx case with a really crappy laser (KHS-400B) and a loose eject button that barely worked. It could only play PS2 CD-ROMs if you inserted a PS1 CD-ROM, quickly ejected the tray, and swaped in a PS2 CD-ROM. It struggled to read DVD-ROMs and DVD-Rs were out of the question. Only a few days after the 30 day warranty expired, the laser fried while I was playing a game.
You get what you pay for, at only $30 (price has since increased)
A few weeks later I purchased my fourth PS2 from craigslist. Let's just say I shouldn't try to replace lasers or touch flat cables haha.