Milions of  cards are availavle in every subject, tv and sports. How do you know Ebay is your best source to find them. Everybody has a favorite card shop they visit, but their inventory may be fairly limited to what you need. If you are collecting a 1961 Topps baseball set and don't care that the cards are poor or good, you can get a grab lot of commons and stars for the fraction of the price. Occasionally better grade cards are thown into the lot which can be used to replace some of the worst duplicates you may have. Also graded cards depending on grade may be a good deal, because someone else paid to have it graded. Always be careful buying vintage packs. I've opened thousands of packs only to find some loosely resealed and lots of high grade commons!  New wax boxes are certainly a great deal if you hit the right card. But remember that it was part of a case and those one per case etc cards were probably already found leaving the other boxes sold on Ebay at a discount. However, stores I have been to always have two missing packs in each box and have never scored an auto or jersey card. The solution: Buy auto'd and jersey cards on Ebay for as low as a buck + shipping!!!  I have a wonderful collection of UD Golf, Football auto and jersey etc. Remember, packs are usually $3-15 bucks each. I've opened these also and got junk. Whether it is vintage or new you can find some great deals or not if your favorite shop doesn't have it. Hope this Helps!