For whatever reason, Quickboost has produced British, German, American, and Japanese gunsights, but never Russian ones. Northstar Models has the following VVS gunsights in their line of accessories:
PAK-1, in 1/72, 1/48, and 1/32:
http://northstarmodels.com/product/172-soviet-gunsights-pak-1/PBP-1a, in 1/72 and 1/48:
http://northstarmodels.com/product/172-soviet-gunsights-pbp-1a/PBP-1b, in 1/72, 1/48, and 1/32:
http://northstarmodels.com/product/172-soviet-gunsight-pbp-1b/Home page:
http://northstarmodels.com/Northstar's service is very fast, well packed for shipment, and economical. I bought one package of each type (4 pcs per package) in 1/72 scale plus some La-5 wheels and received my order within a week; postage to Canada with tracking was only $5.00. In 1/72, I'll probably need a microscope for the gunsights, but at least I have them, plus the satisfaction of supporting a company who supports VVS modelbuilding.
John