it's sometimes worth pointing out that the price is higher than so-and-so other retailer - but politely, of course, if the difference is really not acceptable.
When I bought my guitar amp some years ago, the price at the 'big guys' was £489, but the local shop wanted £589.
I explained that I'd prefer to buy locally, but the price difference was too great. I expected him to knock £50 or so off, as the extra would have been reasonable considering the travel or mail inconveniences, cost, time etc. but after he'd checked the prices on the internet he sold it to me for £489 - the lowest price advertised elsewhere.
Like many owners of 'hobby' shops, he was an enthusiast who spent his time indulging in the 'hobby', not checking prices on the internet. He'd no intention of 'doing' anybody, just put the prices on that had been suggested and got on with playing the guitar. I left him studying prices on the internet - he looked more interested than dismayed.
Human nature being what it is I have never complained to any shop-keeper for under-charging.