When creating partial sets of wheats to sell on ebay, is it worth spending a few extra dollars to pick up a few reasonably priced harder to find coins to help salt the set?
Well - I can't answer your question for lincolns. But some of the shield nickel and liberty sets with key or semi-key dates seem to draw ridiculous money. What you might do is try it with one set to see if the profit is high enough to make it worth while.
Don't know about ebay since I don't use it at all but at coin shows I've seen many Albums of coins just not selling if all the key dates are missing. When throwing in a few of the key or semi key dates, the set becomes more appealing and sells faster and for more.