This is a topic exclusively for my readers who play Lusternia. The question is, if you could have one and only one artifact from Lusternia's shops, what would it be? No changing the rules of how it works, either. It'll be precisely as it sells in Trader Bob's shop, and you can only have one.
Obviously a lot of them don't make sense in the real world. A cubix wouldn't work well if there's no astral plane to go to (and let's assume that there isn't). There's no point in the rune that extends the size of a demesne if you can't have a demesne. What could you do with a font of Maylea if there's no Maylea to make offerings to here? A changeling cameo wouldn't help a lot when we're notoriously short on other sapient races to change into.
Still others, you have to stretch a little to imagine their use. Would a Great Rune of Empowerment make you better at kissing up to your boss at work? How useful would be mana regeneration? If you got a Great Rune of Unlocked Potential and attached to a beer keg, would they charge you less to refill it? Would a Silver Spoon make your vitamin supplements more effective? Would a Merchant's Ledger do anything that a Google Shopping search didn't do? Would a circlet make it easier to tolerate being stuck in meetings at work? And what good could you make out of having a golden mirror, besides confusing the heck out of people? (Come to think of it, that's almost all Lendren does with his/hers.)
But there are certainly some that would be useful. A dingbat scent nose artifact, for instance, could tell you just who was in the local area, which would help in finding people. Faerie wings might draw some stares but sure would be fun, as would a (hover) surfboard. A lot of them would be great for criminals: the shroud of shadows, for instance, would be very potent in a world where no one else has Thirdeye, and spectacles would be great for knowing when the cops were getting close. Who could say no to a candy box that refills itself?
But I think in the end it comes down to two choices. The rune of health regeneration, for the simple fact that it sure would be nice to heal automatically from any hurt that's not an affliction at a remarkably fast rate. (I'd've been back up on my feet an hour after my bike accident, for example.) And a paradox puzzle pyramid, because getting around instantly over any distance would sure be handy.
The fact that the pyramid resets every month (let's say for the sake of argument a real-world calendar month) would be limiting for some uses, of course. You couldn't use it to travel the world, because you'd need to have a way to get there first. However, if you could find some way to make money that way, you might be able to come out ahead. For instance, if you could find someone who'd pay well enough for you to bring something back from Paris every day (maybe some food he dearly misses), you could fly out once, set puzzle points, then earn back the cost of the flight the rest of the month, and meanwhile, get to visit Paris every time you felt like. The next month, find a client who wants something from Tokyo. Only trouble is, where could you find clients like that?
Perhaps the best answer is if you're willing to go into criminal enterprises. After all, you're bypassing customs entirely. The market for fresh New York bagels to expatriate New Yorkers is not nothing, but pales compared to the market for smuggled drugs and other illegal goods. And once you're talking criminal jobs, why stop there? Rent a safety deposit box on the 2nd and set your puzzle while there, then puzzle into the vault in the middle of the night on the 19th and empty it out, then puzzle back out. Let the police wonder how someone got in and out.
But even if you managed to do nothing more with it than make your commute to work instantaneous and zero-cost, that alone would be really amazing. The amount of time, money, and aggravation you'd save would all add up quickly. Add to that the chance to do a little travelling and maybe make some good money on delivery services or import/export, and you could really come out ahead.
(Of course, if you could even get the limited artifacts from auctions... that one that lets you resurrect people would sure jump out, though it raises all kinds of sticky questions.)