Bishop is a clear mistake here, at least before late game and probably ever. It simply trashes your opponents deck basically even more effectively than yours, plus there's lots of other terminals you want. Sea hag into mountebank isn't so bad in general (roughly comparable to going money for mountebank), but here, since you want to get to goons, the money route gets the edge. I think your gameplan here should be to buy silver on $3-4, mountebank on the first $5+ and the next $5, Goons at basically every opportunity, actually starting to grab coppers with the extra buys pretty early. Probably with 8 exactly and only one mountebank in your deck and a goons in play, I'd buy mountebank/silver. And watch for three pile endings on something like curse, copper, estate or curse/copper/goons or curse/estate/goons. Basically I think there's a great chance copper is going to run with all the mountebanking and goons-buying-copper going on.