I bought an iRiver H320 on eBay for I think it was 150 Euro a couple of months ago. It's got a 20GB harddrive, and normally records in mp3 format. But when you install the
rockbox firmware, you can record in wav. It has an internal mic, but I've never used it. Bought some external mics and use it for live music recordings. And it works great, very easy to use once I got to know where all the settings were for.
You could also take a look at some of the other players here:
http://build.rockbox.org/ Maybe some model with a smaller harddrive would do for you if you only want to use it for recording.