As the others have indicated, you'll get much more value by selling it off in pieces, but that also takes much more time. If you sell it off in a single lump, either on eBay or to a major shop, you'll probably only get 40-60% of its retail value. I'd suggest selling off a bunch of small chunks first, especially if members here are interested, and then bulking out the rest. But keep in mind that also has risks; if you sell off all the good cards, you may find that no one is interested in the bulk at all. There's obviously no one right answer...