It is very strong, but I'm thinking it might pose an interesting dilemma when deciding whether to lose it in favor of a Province/Colony, or continue using it to get Golds/Platinums.
Besides, there already is a card that lets you gain $6 cards without buying them - Smugglers.
(As for my other card suggestion, I deleted the topic because, upon further reflection, I realized it really wasn't a good idea).