Big problem with that: unless you live in a megacity or on the Islands, you won't find a music store with a reasonable selection to try. And you'll find almost none with excellent brands like Mainland and Gretsch. You'd have better luck going to a uke festival or local uke gathering—with the added bonus that the ukes people have brought will have opened up and be seasoned by play, giving you a better impression of how yours is likely to sound long-term—good ukes don't always display their promise fresh from the factory.
There's also an ethical issue: if you're not planning to buy from a local retail store (should you find what you're looking for at a competitive price for such stores), if instead you're planning to order from an online retailer who will undercut them hands-down, you really shouldn't be squandering local stores' resources for your personal convenience. If you happen to be there shopping (actually shopping) for something else, browsing is to be expected, but to make a special trip to try their ukes with no intention at all of buying from them is pretty scummy.