I did run across it a number of months ago. At the time I made an offer that was slightly higher than I expected a dealer to make, but considerably less than I would have to pay to buy it from a dealer. Some of it is a gut feel thing (just reading what the person is expecting). In my case, I believe it was a win-win since silver has jumped drastically since I bought the collection such that I could sell all the silver as junk silver (which it wasn't all junk), make a 25% profit and keep all the other Indians, wheats, buffalos, etc. I paid slightly above (about 10%) above what I thought a dealer would offer at the time.
Another data point:
The 40% Kennedys I sold a few weeks ago to a dealer at a coin show were sold at roughly 80% melt value.
With todays silver price of $14.19/oz, that would put the offer price on the "junk silver" as follows:
War nickel - $0.64
dime - $0.82
Quarter - $2.05
90% half - $4.11
40% half - $1.68
silver dollar - $8.68
which is roughly 8X face.
And adjust for condition and rarity as you see fit. $10-12 for the morgan seems about right for a common date average grade morgan.
In regards to the Indian heads, $15 for 3 rolls is 10 cents each. A typical low grade common date Indian Head seems to be in the $1-$2 range at the coin shows I've been at. But thats the dealers selling price, so make an offer that you feel is fair.
I wouldn't have too much of an issue with going up to $45 - $60 or more on the IH if you got a chance to see them and verify that they have mainly readable dates and/or less common dates (prior to 1887 are more valuable, some considerably more valuable). At $60 for 150 IH pennies its still only 40 cents each which is still considerably less than buying them from a dealer (at least what I've seen).
The other choice you have for IH is to ask what type of price she is hoping to get for them. At least then you have some idea what she thinks they are worth and can make an offer based on that. If she won't say, you will have to just guess what she is hoping to get for them.
Basically, depends on how badly you want them.
Good luck.