Also, you have to look at value and worth. Some places are cheap because they should be cheap: perhaps it's worth visiting them if you've already visited the main capitals several times and know them well. But, for example, the tertiary sites of London, Paris or Rome have arguably more to offer than the principal sites of Vilnius or Bratislava. So why waste $2000 on a trip to a tertiary location when you can get a trip to a primary one for $2500?