As a Lego seller, or someone who wishes to begin selling Legos, you must be careful when making your purchase.  After I purchased my first lot, I was astonished to find my precious Legos intermingled with junk.  I'm talking about leaking batteries, fingernails (I am NOT kidding!), trash, coins, rocks, used popsicle sticks, nails, toy cars...are you getting the picture?  Worst of all, my supposed "Lego" lot was about 50% imitation bricks, parts, and pieces.  My seller did not make amends and I was out a lot of money.  I did learn a valuable lesson, though.

When searching for bulk Legos for resale, do a search for "Lego pounds" or "Lego lbs" or "Bulk Lego", etc.  If a lot looks good, check the seller's feedback.  If it is 100%, mark the lot as an item to be watched (you'll find the link in the upper right corner of the listing).  Once you have five or six lots, go to your "My Ebay" page.  The lots will be listed there. 

At this point, you'll want to review each one to make sure the shipping charges are not inflated.  If they are, then delete the lot from your page.  I usually estimate the shipping by the pounds of the Legos being sold.  If you're looking at a 100 lb. lot, then the shipping should not be $200.  It should be closer to $100.  If it's 20 lbs., the shipping will be somewhere in the ballpark of $20.  If the seller has listed the shipping at $50 for 20 lbs., then more than likely, they've inflated their prices.  When you are finished, you'll have narrowed down your search to reputable sellers who are fair and honorable. 

Decide how much you are willing to spend on each lot.  If the lot includes minifigs, estimate the figures at $.50 each (general minifigs resell for approximately $1).  If the lot includes castle minifigs or Star Wars minifigs, figure the price higher.  Calculate the rest of the Legos at about $5 to $7 per pound.  If it includes Star Wars or Castle specialty pieces, the price will be higher.  Just look at other auctions that are about to end and you'll see what the going price is.

Above all, make sure the listing states that the lot is 99% or 100% genuine Lego Brand.  If they didn't state that in their description, then take the time to e-mail them to ask.  It is definitely worth it!