Morgan silver dollars, 1881, set of 20, in excellent condition, what are they worth?

I can tell you that the first and foremost factor in value is rarity, followed immediately by condition.

Factors that affect rarity are how many were minted, what mintmark it is, any minting oddities, and again, its condition. (ie: there are fewer in perfect condition than in abused condition, making the better ones more valuable due to numbers alone)

Factors that affect condition are: dings, dents, scratches, gouges, weathering, cleaning, damage by environment, fingerprints, and toning. Try not to handle them other than by the edges, and dont slide them across any countertops or tables. Handle them gently, every nick costs the seller money.

Cleaning is THE single worst thing a person can do to a coin. Dont do it. Leave it exactly like it is. Let an expert determine what it needs, if anything.

History has been hard on coins, keep in mind that this coin is 125+ yrs old and was carried across the western front in trunks, pockets of cowboys, settlers, hidden in log cabins for years, traded, thrown in the cash register with other coins, buried for years, and slammed on counters of stores and bars for decades.

I wont bore you with the professional grading scale, but it starts with junk value at the bottom, and escalates to mint purely perfect “as minted” condition at the top, or MS70 (mint state 70)

A roll of 20 of them in junk condition will sell for 20x the value of silver, per oz.

A roll of 20 of them in mint, undamaged, perfect condition, will sell for much more.