A Reserve means that the seller will not sell the item for less than the Reserve. So if he tells customers that the Reserve is $100. and the customer bids $99, he will not accept payment and he will not sell.
EBay charges sellers for this service.
Add the shipping cost he states to the Reserve and decide if you really want the item at that price. If not, since your current bid is lower than the Reserve, you can move on to a different listing.
You should be aware that if there were no Reserve stated, that your bid remains active until the auction closes.
For example, the opening bid is $10.
You bid $15 but are later out bid by another who bids $20.
Then in the last few hours of the auction, the other bidder retracts his bid.
The top bid is now your $15 and you win, even though there was another bidder for most of the auction.
