Well, for those of you that are having difficulty with the game, here is a little help.
Note that this will make the game significantly easier, at least on the first two levels.
SPOILERS ON SECRET SCROLLS!!!!
Go through the first level and get about 5k gold. After that go into the secret shop and buy D1, D6, C1, B1, B6, A1, S1, D3, C6, B3, and then A5 in that order. This will net you all the handgun upgrades and a bit of spare cash.