Merchant Road is a Treasure that adds a non-Supply pile of Goods which are always non-terminal (to make it easier to get multiple in play). Your first few plays will gain Goods and later you can get rewarded for playing lots of Goods. It seems kinda fun to not have a cost limit on Goods so there's a wider range of possibilities, but it maybe needs one, there's a big difference between a Pearl Diver gainer and a Grand Market gainer. Thoughts appreciated.
The way it is worded, it might not be fully clear that Goods could be any non-terminal Actions rather than ones that give more than one +Action. It's also not clear if this includes cards that conditionally give +Action, e.g. Conclave.
I personally don't think there needs to be an upper limit on the cost of the cards you can set aside as Goods, since the probability of having games with
overpowered strong combos like Grand Market-Merchant Road will be fairly small, and it's not like Merchant Road is that cheap anyway.
That said, Merchant Road might seem expensive if you have cheap cards e.g. Candlestick Maker as Goods. That could be avoided by making the Goods an extra Kingdom pile, so that they can be gained by other means, rather than a set-aside one only accessible through Merchant Road. As such, building a deck with Merchant Road as the main payload would be feasible. I mean, there is always the chance of having something like Bounty Hunter as the Goods, so IMO minimizing the probability of having "bad" Goods might not be a bad idea.