Look for a medium format Durst. Others to look for are Meopta (cheaper but very good quality), Kaiser, Dunco, Devere. If you are on a tight budget look for a Krokus (Polish) or one of the Russian models. You should be able to pick up a Gnome (UK made) for close to nothing.

Beseler and Omega are common in the states but not so much in the UK. If you are going to get one of these it is best to get the 4x5 models.