Well the primary download site (my website) has 250MB/day bandwidth (7.5GB/month) - not bad considering it's a free ISP site - should be fine for the actual plugin downloads.
If the plugin is, say, 2MB (I don't actually know the exact size) that's over 100 downloads/day which will be suitable provided the plugin doesn't get popular beyond sanity.
Hosting & Bandwidth for the sounds etc would be useful I should think tho (I dont know who'd get emails from my ISP about going over my bandwidth limit but if it's mum I doubt she'd like it lol)