but I will narrow it down by a few - be wary of Toshiba Gigabeats (40GB mp3 player, decent weight and size). Those things tick me off, though. I had one & it was a pain getting my music to play on it (not simple copy-paste - you need to install software to convert your music into a format it plays and even when you do, some of your music still won't play). For some reason it wouldn't play my converted songs (shrank 'em from 192 to 128/160). Also, forget about viewing your pictures - had no luck in moving files.
If you have unconverted music and don't mind installing and converting your music, it might be a different story but for me, it's best suited as a USB HDD. Another is Microtek (20GB media player, lite), good mp3 player, decent radio reception but stinks playing video (you need to convert to 3GP to play anything and it needs to be a SMALL file to play decent).
A 3rd is the SmartTrax FlashTraxXT (40GB), I don't know about you but I wouldn't buy this from eBay or in "refurbished" condition - go elsewhere - you'll pay more but I would have rather got this one new. This one worked for me for a few mos. w/ some issues. Mainly concerning times when I start it up only to get no response.
Right now the display seems to have gone out. In terms of performance, though, I consider it a great media player. Plays most, if not all music formats (ogg, mp3, wma, etc.) and a select number of video formats w/ good crisp quality (if you don't mind squinting a little). Lets you play and record radio broadcasts too.
However, seeing as the FlashTrax is somewhat bulky ('bout the size of a small brick :)), I'd suggest putting that $300 to an iPod Classic (I'm considering getting 1 for myself once I save the dough). But don't just listen to this forum, do some research too. Check online at different sites (newegg, tigerdirect, resellerratings.com, etc.), look at their consumer ratings & see what problems are common w/ these players.
Sorry about the long post. I know you said you were looking for an mp3 player and I gave a small synopsis of media players.
Just my 2 cents.