When I'm asked for advice about buying jewelry on a cruise, which happens pretty frequently, I tell people to stick with the retailers that the cruise line recommends or buy from the cruise line, That's the only way they can be assured of any recourse if there ever is an issue.
I also tell them that there's no such thing as "buying at wholesale" from any retailer, here or abroad, so it's fine to buy a momento, but don't make a major purchase because you think that you're going to get a good deal because you're closer to the source. You won't. There won't be anybody to talk to if there is a problem. I recommend that they treat any purchase they make abroad as a gamble,just like if they are playing in the casino.
When you are away from your local market, only spend what you can afford to lose.