In Prague;
Pavla Najmanova ? czech model agency
United Modeling
In Budapest:
Sandy's Models
We've shot extensively in Prague and the models are great there. Punctual, look like their pictures, work hard and super nice. I've heard that it's illegal to shoot in Russia so the Russian girls travel to Europe to shoot.
I would recommend only going with one agency no matter which city you shoot in. Most agencies will give you some sort of deal of their end and they can juggle girls schedules.