Just a small note to those that don't want to pay full price for a "floor model". In most cases that really only works for instruments up to about $600 or so and often not even that much. Unless the instrument is affordable and popular enough to justify having a stock of them in back, for most "better" instruments the one on the floor is the one they have.
Not to say that I agree with the manager in the OP, but retail of high priced instruments is low volume and low profit. A retailer shouldn't be expected to discount every "better" instrument as a floor model just to keep them in stock.
In general, I think that simply having instruments on a high shelf out of reach or behind a counter is enough of a deterrent. Some tire kickers will still ask to have them brought down, but it massively cuts down on the number of hands an instrument passes through.