Nofan, it is not always best to compete with your competitors on price alone. You might wish to consider increaseing your prices and targeting a different market? Or offering "premium support" or something to that extent...to make your clients pay for the extra mile service.
Budget hosting has many drawbacks...more clients, increased resources, downtime...more support to handle. IMO, ten good well paying customers is better than 100 bottom feeders. However, if you still wish to follow in this market....i have heard
www.poundhost.co.uk do cheap resellers and also might want to look into
www.managed.com.