I use 247-host.co.uk, their reseller package is $5.99 per month - with cpanel and fantastico, the bandwidth is 20gb i think, but then my sites are only new, so at the moment its not a problem. their service has been excellent as well.
Well, as I remember there is a data transfer limit per day. I guess it would be 600GB/number of days in that month. So, if the limit was 20GB and you used 30GB then you'd be charged for the extra usage. Also, registering additional domain names with them is expensive, but then I use godaddy and 123-reg.co.uk for my domains. It's a great host. mysql database will be stored on other, dedicated servers and when creating a new database it's not always the same one. The support is very quick to respond (so far, within a few minutes) and always extremely helpful and friendly.