The apparent answer...
How Much is a Fancy Cancel Worth?
As with everything, it is a matter of opinion. As I said above, fancy cancel collectors will keep stamps that other collectors will reject. Bill Weiss has an excellent state of this in his book on New york Foreign Mails, I'll quote this one day if I remember to get permission from him to post it. One important factor in prices for Fancy Cancels is the quantity in which they are purchased. As with any stamps (or other purchases) one can buy thousands of these for less then a dollar each and find a mix of stamps form a few pennies to many dollars. Purchased individually one must pay for the dealers handling.
A worthless 3 cent green with a tear and a thin with a boldly struck unlisted shield is still worth a few dollars. The same stamp would be thrown away without it. The same shield on a perfect 3 cent green might go for $30 to $75. With a listed shield the value might go up to $35 to as much as $100. Depends on the shield. If it is a complex shield the value goes up. If it's a Waterbury the value goes up. A shield with stars is more valuable. One with an eagle is even more so.
What about a shield on a 7 cent Banknote? The value could go up considerably. A perfect 160 catalogs about $90 - might sell for close to that in VF/XF. With a shield cancel - let's say a simple, but nice one - it might go for $135 - or even more. It depends on just how pretty it is and how many people want it that week.
65s catalog $2.50 each and can be bought for pennies each in quantity. With a mix of ordinary Fancy Cancels they can sell for a dollar or two each. With nice cancels - the skies the limit.
The classic example of the value of a Fancy Cancel is the Running Chicken. The famous cover has a strip of three of the 1c 1869 (112) on a very nice cover. My guess is that that cover without the cancel would sell for a few thousand dollars - maybe. With the Running Chicken it last sold for $275,000.
Of the four main books that I use (Cole, Skinner & Eno, Weiss and Herst) only Herst tried to give a value range. He was a stamp dealer so I guess we can understand that. Weiss is an auctioneer and he only give three indications - Common, Scarce and Rare. Cole uses a range of factors from -I to III+. I find this quite useful, but I disagree with some of his values. Skinner & Eno gives no indication of values or scarcity - nice project for someone.
So what's a Fancy Cancel worth? Depends on just how pretty it is and who wants to pay for it.
http://uweb1.superlink.net/~frank/myopinions.htm-IBFS