Low powered on-gain options are a neat idea, but keep in mind that on-gain powers are a bit weaker to begin with, since you only get to use them once. $4 seems a bit expensive for the options you list, since the card doesn't really do anything otherwise. I suppose it has its place in a Conspirator or Scrying Pool deck, but (as has been pointed out) may not be worth enough to be really great with TfB.
Simple cantrips seem harmless, but they can actually decrease the quality of your deck because they A) can be drawn dead and B) decrease the amount of information in your hand (sometimes you'd rather just know what the next card is).
Right now it does seem like the trashing option is the best. I'd only want cantrip+Silver over just Silver in very specific types of decks that I mentioned, and 1VP just seems like too little. I think it'd have to be 2VP for it to be competitive on a lot of boards.
Maybe you could make it a $4 village (+1 card, +2 actions) with an on-gain bonus, that might make it priced more appropriately. Or, make it a $3. Another idea might be to add an on-gain self-Spy option (reveal and optionally discard the top card of your deck).