A reserve is a minimum acceptable price a seller puts on an item (coin in this instance). For example, if I have an MS-63 1892-CC Morgan (high value coin) I want to list, I know it's gonna sell and I expect at least $1700 for it. However, I'm not positive it will actually sell for that much and to protect the money I've already got into it, say about $1500 including grading and slabbing, I'll set a reserve of $1500 so I can at least break even. If the bidding doesn't reach $1500, I am under no obligation to sell it to the highest bidder, so my investment is protected. The catch is that
ebay charges a LOT for a reserve auction if the reserve is not met. It it's met,
ebay charges only the normal Final Value Fee plus listing fees.
Sellers handle reserves in differing manners. Some state what the reserve actually is while others, myself included have a hidden reserve and do not state what it is. I do the latter with the hope that someone out there will keep bidding out of curiosity or frustration in an attempt to learn what the reserve might be. I also give "hints" about the reserve in my description, i.e., "well below price guide listings" and "below recent completed
ebay sales". To me, stating the reserve price is little more than a high start price thus keeping bidders away. Sometimes it works and sometimes it doesn't.
On occasion, someone will message me asking what the reserve price might be. No problem, I let them know. Many bidders are budget conscious and want to know the numbers of zeros after the dollar sign to determine if the reserve is in their budget.
Fred