I've always had this idea for a reverse bridge, and I created a working version a while ago and posted it to reddit, I thought I'd post it here too to see what you all think of it.
Refine
$5
Action
+1 action
You may trash a card from your hand. If you did, you may gain a card costing up to 1 more than it.
Then, cards in your deck not gained this turn and cards in the trash cost 1 more this turn.
It is a TfB card that also synergizes with most other TfB cards. It can be comparable to Upgrade except it is better because the TfB is less picky and it builds on itself and other TfB, but it doesn't draw you an extra card to compensate.
The reason it affects cards in the trash as well as cards in your deck is to make it work functionally as well as thematically. It makes your cards more expensive, and when you trash them, they need to keep their higher price in the trash in order for it to function.
The reason it singles out cards not gained this turn is because of reddit poster bluey_the_bear who pointed out that Livery lets you gain a horse everytime you gain a card costing 4 or more, so if the moment you gain a card costing 4 or more with Refine in play, everytime you gain a horse it also costs 4... allowing you to gain the entire horse pile. He pointed out a few other broken card gaining abilities, so in order to make these impossible, I changed the wording to specify it doesn't apply to cards gained the same turn you play it.
Overall, I think this is a great card that is a worse upgrade the first time it is played, then a better remodel the second time, then a better expand every other time. I would really like to playtest and tweek it more if needed, so let me know what you think.
Also, here is the link to my post for this card on reddit.
https://www.reddit.com/r/dominion/comments/ghrt2j/card_idea_refine_dominion/