When you say BIN, do you mean fixed price?
If you use the bulk relist function for unsold auction style listings, you can change the format to "fixed price" and the starting price for the auction becomes the fixed price by default.
However, it does not work the same way in reverse.
If you bulk relist fixed price listings and want to change them to auction style listings, eBay - by default - will insert $0.99 as the starting auction price and the fixed price as the BIN (buy-it-now) price. It takes a while to change them manually.