A few years ago I ordered some 128 MB DIMMS from them for my Power Computing PowerTowerPro.
The first batch they sent me - 1 out of 4 DIMMS worked
The second batch they sent me - 2 out of 4 DIMMS worked
The third batch they sent me - oh yeah, they sent me PC RAM - whoops
After that I did some poking around online and discovered that memory4less was using PC RAM and flashing it for Macs. I ended up sending back 2 of the 4 dimms I purchased from them for a refund - they never could get it right.
I'm not sure how they would be now - the current lineup of Macs use totally different RAM now. if you don't mind going through the return hassle over and over - sure - go with them. If you want stable RAM go with a more reputable vendor - Crucial, Kingston, etc. - more expensive but mostly headache free.