We are going to Russia for the first time this fall and have rented an apartment in Petersburg for 10 nights. This meant we needed visas. We obtained invitations from the landlord, and then applied by mail. Since we live in Chicago that meant Washington DC. The cost was 160$ for each Visa and 70 for mail processing (I think it is 35 if you can walk in and pick up). I paid an extra $25 each so that if there were errors they could correct them. But our applications arrived water damaged and so instead of them fixing the errors, they just sent everything back and we did it again. I packed the materials in a plastic bag inside the USPS priority mailer the second time and it worked fine. They also sent back our two $25 fees for fixing errors.
Once they had the completed material, it took two weeks. The $160 Visa fee is the same for a single entry or a 3 year visa so we got 3 year visas. If we love it, we may go again next year.
It is pricey which suggests spending more time in the country -- I didn't realize how pricey when I planned, but the process at least so far has been smooth and the contact at the company that processes these things was very helpful.