We own, and love, our PS3. Your probably not going to find any deals on them, seeing as that they just lowered the price a LOT. (Down from 4-$500 to the 3-350 range).
Regarding the hard drive size. I own an older 40GB model, and the drive is maybe 25% used. The only way your going to fill it, is if you start downloading movies, add ons etc. etc. If used as a game machine, and blu-ray player, the 120GB is going to probably last you until the next model comes out.