Good fits
Haggler Not only does he give you extra buying power, but he's able to talk the seller into throwing in a little something extra. What a guy!
Trader This suave guy is able to interject and sell something for silver, even before you realize that the mountebank gave you a really bad deal. Also, any card worth anything can be sold for silvers.
Noble Brigand He steals only from the rich, and he gives to the poor. Granted, he's not that great at it, since he fails to see the value in platinum. And he only gives copper to the poor. Still, he does rob from the mostly rich.
Thief He steals treasure. You decide whether you want to take the Thief's loot or not.
Scheme Bigger plots ahead.
Fool's Gold Is it valuable, or is it worthless? You'll just have to find out.
Remake/Remodel Out with the old and in with the new. Literal implementation of these names. I actually don't consider Expand to count, though.
Sea Hag/Witch/Young Witch You curse someone and make their lives miserable. Very MacBeth. The Young Witch isn't quite as effective and is easier to circumvent. The +2 Cards aren't really that thematic for the Witch, but when you consider the +2 Cards, then the Young Witch is even more thematic by not being as good at that either.
Stash You pick where it goes so you can make use of it later (or right now).
Black Market You want something? Limited time only. One of a kind. Get something that you can't just get from the regular market.
Bank Use money to make money.
Contraband It can make you some pretty coin, but you have to dodge the authorities. This may mean that they prevent you from getting to your contact.
Rabble They tear up your store fronts and make a general mess. You may have to spend some time digging through the mess.
Mountebank Really, your opponents should have thought better about buying these little blue pills on the street corner.
Transmute You literally transmute one object into something entirely different. It's magic!
Possession Dance, my puppet, dance!
Workshop/Ironworks It creates something. It's not impressive, but you have a new toy now.
Spy/Scrying Pool You can see what the enemy is planning and act to thwart him. You also see what obstacles may be in front of you too.
Bureaucrat He makes your life easier. He ties up the others in red tape.
Trading Post Similar to the Trader, you can sell off a couple of items for a Silver.
Saboteur Valuable thing goes boom. This would be more thematic if the item was not replaced, but that'd be an even bigger dick card.
Coppersmith Making Copper more valuable.
Wishing Well Star light, star bright, how I wish for a Harem tonight.
Scout He may suck, but he literally helps you look ahead. He also helps you circumnavigate around quagmire.
Swindler I know you were told that you were buying a chapel, but you get this pearl diver instead.
Pearl Diver Physically diving to the bottom of your deck to look for something valuable. Sometimes he comes through. Other times you get a tire.
Torturer Do this or suffer the consequences.
Masquerade It feels like an anonymous dance.
Navigator "Should we take the route of the Cursed Garden?" "No, I think we'd be better off sailing around it and entering lands unknown."
Treasure Map Sometimes you find X, but you usually only have a worthless piece of paper in your hands.
Cutpurse Small-time thug can lighten your load. If you are rich enough, then you probably are too risky for him to tackle.
Meh
If it's not on that list, I probably don't think it's a good fit.