If you draw your deck, or almost, you can gain basically anything. Gaining Gold (always available) in turns 3 or 4 is pretty easy, since you only need to have an Estate in hand. Plus, you get to maybe buy something, and get an almost Chancellor effect. I think you should at least make it impossible to buy something more expensive than the number of revealed cards.
I like it like this, which also adds a bit of flexibility that may add some deck-handling tricks:
"Name a non-Victory card. Reveal up to 10 cards from your deck. If the revealed cards have a total cost less than or equal to the cost of the named card and the cost of the card is less than or equal to $1 per revealed card, gain a copy of the named card. Put the revealed cards in your discard."
Notice the text does not trigger when-discard effects (like Scavenger and Chancellor), basically to avoid Tunnel becoming insane. I think it would even be worth it to let choosing the card after the revealing. That cap will make it simply not work with potion-cost cards.
This could be a nice submission for Guilds Treasure Chest contest, especially since Guilds does not have a gainer (Stonemason is probably closer to the Remodel-family).
EDIT: Notice that this can guarrantee a $5 or $6 with similar odds to Baron or Silver, respectively, as an opener (if you double-open it or open this and nothing). That seems reasonably powered. Also, if your engine has good manage of your discard (Scrying Pool/Cellar for instance) you can use this to gain pretty good things, which is nice. As long as it requires skill to make it work, is great that you can make it do great things.
EDIT 2: I would even consider removing the non-Victory clause, or maybe just trash it on Victory-gaining if it ends up too powerful, like HoP does.