Are the +3VP a bonus you get each play or something you get at the end of the game?
At the end of the game, they are similar to an idea that i think Donald rejected. Giving points for Provinces is a bit boring, as you are trying to get the most of those, anyway. The difference would probably be that this makes you buy your card and Province in an alternating pattern, similar how Duke does with Duchies. Just with the difference that there's no real way to avoid participating in the "Province race".
If it gives the +3VP every time you play it, it's not only too strong, but also takes a while to resolve, as you'll have to look through your deck and discard pile to find all the Provinces.
Copper is usually a card opponents want to get rid of - and you want to, too. You are almost always better off with doing a bonus that doesn't make you gain those bad cards and doesn't scale with different amounts of players. Cutpurse and Pirate ship both avoid it (Pirate Ship gains 1 token regardless of the number of trashed cards, Cutpurse gives straight +$2). Thief does both, but Donald recently said it makes him look bad as a designer, and
Noble Brigand does scale with different player numbers but at least provides some non-scaling bonus and doesn't gain Coppers.