A lot of times, my deals are BIN, but my "secret" is
communicating with the seller and making offers. More often than not, my offers are rejected or go unanswered, but for the deals I do get, it's definitely worth it!
One thing that works in my favor is that many sellers have no clue what the "market value" of their bags are, so even if their listed price is pretty low,
I always ask if they'll go lower and I always say that my "offer" includes the shipping price. Also, if an item is ending soon and it's an auction without bids, I say something like, "I saw that the listing will end in less than an hour and there aren't any bids. If it doesn't sell, would you consider $xx?" So on one hand, sometimes I get lucky and the bag doesn't sell and the seller accepts my price after the auction ends, but a lot of times, I "miss out" on bags because someone else bids. At that point, I could bid and pay the listed price, but I get this set number in my head of what I am willing to pay and won't go over.
However, for this bag, there was a reserve on the price and she had had the bag listed previously. After the auction ended, I asked her if she would consider selling it for the price it sold for and she accepted.
To sum it up, yes, a lot of my finds are technically BIN, but they start out as auctions that don't sell or the seller agrees to add a BIN price for me. HTH!