Downtown is really, really weak. It's basically a one-shot Workshop that's non-terminal, at the cost of everything being more expensive this turn. Workshop is already pretty weak and it's not a one-shot. Of course, you don't have to trash this for a $4, but in most cases you would want to, because it's not worth paying $1 extra just to get 2 actions. It does interact with TfB, which I think was your goal, but it's really a dead card on boards without TfB. And more importantly, on boards with TfB, it's not so great that I would generally be willing to get it. Sure, it means I can draw an extra card from Apprentice, maybe get an extra VP from Bishop, and Salvager gets an extra coin; but that's about it. Almost all TfB cards care about the cost of the trashed card, with a reward of gaining a card with some cost relative to the trashed card. Even in the three cases where it is helpful, it's not very good; Salvager's extra $1 is only enough to make up for the price increase, so it probably shouldn't even count. You can think of Apprentice's extra card as making this into a cantrip, which clearly isn't worth it. And the extra point you might get from Bishop, well now we're talking about one combo that this card has, which isn't really that great, and you're making the card basically just for that one combo. Stacking these doesn't help, because you need at least 3 of them to make a 2 VP difference off of Bishop, and you're basically killing the rest of your turn at that point.
Inflation might be a little better but really, I don't think it combos with TfB cards like how you want it to. The extra buy probably does nothing most of the time since costs are increased, and the +$1 cancels with cards costing 1 more, so basically you would only be playing the card to trash it. If you can get an engine going that can play like 6 of these, then they're pretty good; that's 5 VP each. But that's going to be way too hard to do most of the time, and they'll probably just end up being a slightly worse Island (since they get you 2 VP that doesn't stay in your deck).
If you want to get interesting interactions with TfB, you might want to have some cards have their prices increase but not others. That way, the trashers that reward you with some gain can actually benefit from these cards as well.