According to Central Bank of Russia 1 USD is approximately equal to 5000 BYR.
If you pay with dollars and get BYRs then 6000 is quite a good sum.
If you pay BYRs for USD 6000 is not very good but also is not a vicious robbery since BYR lost its real cost twice in May and is still unstable so people don't rely on BYR and change it to USD which in turn rise the market price for USD with respect to BYR. Though an advice of a Belorussian would be more up to date.