You could try these - http://www.tripod.lycos.co.uk/ - I use them for a website on which I put Real Audio files. They are a lot smaller than mp3, but they don't seem to impose any limit on file size, and teyh total 50MB is enough for a few MP3 files anyway - and I'm not sure they actually pay too much notice to the limit.

And you'll see if you visit my website that banners aren't a problem (well they haven't been so far, touch wood)