Hi,
I host my own sites on a service provider called "Linode". You can taylor your package at any time (if you need more memory, more processing power, more bandwidth, whatever) it call all be added on with absolutely no downtime on your server.
You can even rent "emergency" bandwidth for example if you get a sudden rush of data over some time frame.
If your current backend is set up with PHP, MySQL then I can set you up a Linode (you of course have to purchase that, which is about $10.00 per month roughly), and migrate all your existing code plus your database over to the new server.
It should take me about a day to do.
Just send me a message if you have any questions.
Thanks
John