I wasn't advocating it, but i certainly understand it: how many dealers have to spend time on folks who are never going to buy from them (seeking out a better deal, buying used, on Audiogon, let alone the perpetual 'shopper' who will never buy). I would assume most dealers pre-qualify their clients if they can- I know I won't waste the time of the few I buy from by asking to have the thing loaned to me for trial in my system unless I am fully prepared to buy it.
You'd be surprised (maybe not) at the number of time wasters, tire kickers and inveterate 'shoppers' there are for all things, from exotic cars to expensive houses. It's almost like a sport. I'm not suggesting that the OP is any of those, but would reckon a guess that he's never done business with that dealer before? That could be part of the answer- not a good answer, to be sure. If the OP had any sort of relationship with the dealer beforehand, it would be an outrage.
On the other hand, the idea of a charge for an in-home trial, particularly if it involves something like a large speaker and the time and effort involved in transport and set-up, is a little different than an in-store demo. Granted, the dealer would make his profit back on the sale without any sort of pre-paid demo fee. And, if it was a question of a deposit to cover the value of the goods, that would be far in excess of $250. Again, i think it comes down to the dealer properly qualifying the buyer. Back in the day when we had a place that was considerably larger than the one we live in now, we had a rug dealer who was more than happy to leave hundreds of thousands of dollars worth of antique rugs on 'trial' at our house for months, in the expectation that we would buy one. And we did. That of course, was a different economy and he had a pretty good sense we weren't con artists.