According to SVO website, you can buy access to Galaxy lounge in Terminal E for 1500 roubles (approx. 49 USD). There are also lounges in Terminal D, however, the website does not mention a pay-to-enter option (which does not mean that such option is not available). All of these lounges are airside and (except one local lounge in D) in the international area.
I haven't been to all SVO lounges, but the ones I visited were pretty mediocre at best.