Well it really depends on how much bandwidth are being used, Although 5 sites that are just being started should be fine with about 1GB Space, 40GB Bandwidth (Or around that) I can offer you some custom proxy hosting (DirectAdmin CP, Hosted on our Toronto server). Check out our plans at http://www.connectproxies.net or email for a custom quote
I think that you'd better start with VPS. If you do npot mind - have a look: http://serverpoint.com/english/virtual-private-server-hosting.phtml
Have a look here http://forums.digitalpoint.com/showthread.php?t=662589 . You can host all 5 sites on the same hosting account to start off with if you like.