I, out of necessity have to order vinyl on line. My favorite so far is Elusive Disc. Good prices, frequent sales, fairly quick shipping and they stand behind what they sell. My attempts at buying used vinyl has been hit and miss due to inconsistent grading. Mosaic Records is not bad, but if an item is out of stock they will hold your entire order till it arrives. You should also check out Acoustic Sounds and Music Direct. Have fun!
Jerry