Mr. Siskin is correct. You'd lose the auction, and nobody would win.

In your example, with initial bid of $50 and reserve of $100, there would have to be about 50 bids using the normal eBay increments to get to the reserve. The seller, by setting things that way, would be hoping for some type of bidding war, since the initial bid and the reserve are just too far apart, unless of course the item is in very high demand for multiple buyers. I'm with you, in that if the seller wants a minimum amount, just set the initial bid either at or close to that amount.

I've lost a couple of auctions because not enough bidders were interested enough to continue bidding to reach the reserve. In one case, the seller immediately relisted the item with the same pricing construct, and I ignored him and all of his listings with reserves from then on. In the other case, the seller sent me a second chance notice stating that I was highest bidder and although my bid of $x was less than the reserve of $y, if I still wanted the item for my bid of $x, I could have it. I accepted that offer.

Some sellers are better than others. :-)