I had a similar experience last year but with a happier ending. I needed a new tire for my Aprilia on a Monday while on a trip. The Hon/Kaw/Suz/Yam dealer in Wytheville, VA had a tire that would fit but wouldn't mount it on an Aprilia. Next I called the local Victory/Polaris dealer. They also had a tire. They said come on over. I was in and out in about an hour, tire mounted and balanced for somewhere around $150. The name of the dealer was Hilltop Cycle.
Obviously you got a more expensive tire but $120 for mounting?? I think I paid $45 or $50.
I ride, Therefore I Am.