You know what? I think I've identified the source of the confusion here between my interpretation of the card and your intention for it (the same confusion has manifested both in this question and in my Conspirator question).
I'm interpreting "Play this as if it were..." as the on-play instructions for the card, similar to Throne Room's. So for instance when you play a Throne Room, here's what happens:
- I put the Throne Room card in play. "I play a Throne Room!" What do I do now? I read the instructions on the card. Oho, it tells me to choose an Action in my hand and play it twice. I'll do that! Let's play that Smithy from my hand! Twice!
In other words, playing the Smithy is a separate event from, and a consequence of, playing the Throne Room itself. In the same way, I was visualizing Band of Misfits as this:
- I put the Band of Misfits card in play. "I play a Band of Misfits!" What do I do now? I read the instructions on the card. Oho, it tells me to play it as another Action in the supply. I'll do that! Let's play it as a Smithy!
So in this reading, playing the Band of Misfits as a Smithy is a separate event from, and a consequence of, putting the Band of Misfits in play to begin with. But that's not the interpretation I infer that you're intending for the card text. What you're implying, if I follow, is that "Play this as if it were..." isn't instructions to execute as a result of playing the card, the way Throne Room's text is; it's instructions on what playing the card actually consists of. So the interpretation you're telling me is this:
- I put the Band of Misfits card in play. "I play this as a Smithy!" What do I do now? Oho, I draw three cards. Okay.
Right?
If this interpretation is correct, and it sounds like it is, then what happens if there are no action cards in the supply that cost less than $5? Does that mean that you can actually NOT play a Band of Misfits, making it essentially a dead $5 card in your deck?
(either the kingdom has only $5 or above cards in it, or the only cards costing less than $5 are treasure/victory cards, or all cards costing less than $5 have been emptied already)
Note that if you have Horn of Plenty, being allowed to play a Band of Misfits without having it imitate another card can make a difference in how much the HoP is worth. I'm sure there are other reasons people can come up with for wanting to play a Band of Misfits even if it's not possible to imitate another card.