Found an LUA edit that works! If you edit the economic_cost values in both the regular policies.lua file and also on the file 100_base.lua, which is located in the "share\fotw\policies\" folder, it will make the card costs negative.
Oddly, it won't change the way that the prices look on the cards themselves...those will still look like the regular costs. However, when you attempt to play those cards, it WILL give you the money rather than take it from your bank.
I haven't tested yet whether you really need to edit both of the files, or if editing just the 100_base.lua file will work, but I wanted to let you know that it definitely does work with both of them edited. So at least we're back in business from an LUA standpoint!
Edit: Hmm. Well, although it does work (I played through an entire scenario with no problems), it only works if you actually have enough cash to play that particular card. If you don't, for example with the $1000 cards in the tutorial mission, then it won't let you use the card. Even though it would give you a negative value of cash. Sooooo, kinda weird, but hey. Better than nothing, and doesn't cause any crashes as of yet. (And once you've made it through a turn or two, you will have accumulated enough cash that you won't need to worry about it. ^_^ )
-Kunou
[Edited by Kunou, 4/26/2011 1:25:14 PM]
Found that file as well and tried changing both 100_base.lua and regular one.
Cards in game did show negative values, but they didn't add money.