Do you really know that? Coming from a shop owning family, not archery but sewing supplies, it wasn't unusual for my mother to sell a machine for very close to cost in order to gain a permanent customer for fabrics and trimming. We've all heard of this in many ventures; "I'd just about give you one of these just to get your parts business". The other shop may not be making much at all.

I would still be very up front but friendly with your original shop, and let them know you need some latitude. Don't expect them to give you a $120 break, but a little more than half that would start into the reasonable range.