That's a great bottle. I think even with the damage, it is worth more than $100. It has many good features: Color, the pontil, the age, and the fancy embossed logo.
Yes, anytime you see a similar one actually sell, that is a good indication of value. Any of the auction sites are good for value information, Hecklers, Glassworks,Ebay,ect...
Just remember, the auction houses deal mostly with near perfect specimens, as well as individual bottles that may be higher in value because of a desireable shade of color or some other attribute that might command a higher price...
In my opinion that bottle is worth the trouble of rebuilding the top. it is normally done with a colored translucent epoxy. It would restore it to a nice display.