I was originally going to put a wallet upgrade in the quest, so that the rupee demand wouldn't be so bad, but I decided against it (plenty of extra stuff already). The thinking is that most folks would skip the bomb upgrade until some later time when they just have it at max anyway (you're not likely to need that many bombs). With that in mind, I sprinkled in some 10-rupee prizes in there so you should have enough for the needed arrows. Then, the money-or-life room.. I was just being mean there.

The mirror shield room is one that I died a lot of times on myself, so I know how hard it is. I actually turned the difficulty down on it a lot. It originally had like 4 blue wizzrobes. I don't think you can get stuck there, though. You shouldn't be able to get inside the enclosure if there are any enemies (aside from the red bubble). If that hits you (which is really unlucky as I placed the water there for you to use the ladder on and "hide"), then you can leave to the east and go up, up, left, and down to the blue bubble and then down again to try again. If you're out of rupees, then you can leave the dungeon. If you're out of bombs, you're still not stuck, but it does give you less leeway. If you're out of both, I believe the wand is all you need to totally escape the dungeon (and there is always the shortcut near the end of the level). The enclosure's wall being removed is supposed to be permanent after you trigger it the first time though, so the fact you got into the stairs should mean that you're able to leave the room.

Maybe I'm misunderstanding something?