after playtesting, unfortunately this still somewhat has the 4 Crowns and a Chapel dilemma.
just keep buying 2 Estates every other turn until they're gone and rack up your VT.
Well, if you have crossroads, watchtower and three goons, you can do this, too.
Just play crossroads, then the goons, buy 4 coppers, trash them all, repeat.
Or use Kings Court, Goons and a chapel - that works nicely, too.
What (arguably) makes crown more powerful than goons here is basicly that it needs no crossroads/KC for it to work.
On the other hand, you cannot just buy things costing 0 with (my idea of) crown, and also you don't attack by playing it. Also, you need to take some turns to trash the estates inbetween.
If it costs 6 and only produces 1$, i do not see it to be actually overpowered for it's price. There are several cards in official dominion that are just absurd if you manage to build a golden deck around them, especially the cards giving VP tokens. And chapel is a fantastic card itself. Even 2 Salvagers and 3 Stashes can guarantee you a province every turn...