As far as I know the best wineshop in Prague.
It is in…read morewalking distance from Namesti rebliky or Dlouha tridy and offers wide selection of (mostly czech, but also imported) wine with reasonable prices(strats somwhere around 120 CZK, I ussualy chose something between 150-170 CZK and never had wine which I did not like) .
Staff is very nice, know what they sell and can help you choose right wine for you (even give you some samples).
You can also order online at vino-klub.cz, where you can find over 4000 wines and pick it up here.
Price is same online as in wineshop, so if you are not looking for something specific you can just walk in, choose buy, drink in house or take away.
They close at 9 PM, but they are open longer from time to time. If you are walking around after 9 PM and craving wine you can try to drop by.