I've been to more adult shops than you could possibly imagine, and all kinds too
Yet in all my experience of these stores, I've not once stepped foot in a place that did not allow browsing. Most places have signs up that say if you wish to inspect the merchandise you should take it to the counter and get assistance, but generally they encourage you to poke around because they want to make a sale. This guy must be independently wealthy if he's not interested in making a sale.
Find yourself a new store--a good sex shop should have a staff that is willing and ready to assist you, is not overly intrusive, and most of all, polite.