Hmmm would probably be a good idea if you made it as a mod, and don't change the game files. First make a folder in your mod folder (you can find it by going to options and then mods, then find folder, inside the game). The name of the folder you make will be the name displayed in the mods menu in the game. Now go to your install folder and copy your gameinfo folder over to your mod folder (if it is for entrenchment the copy the gameinfo folder in your entrenchment folder).
After this you need to convert the files in the gameinfo folder from bin to txt files, you can do this by using Harpo's bin to txt converter which you can find in his utility thread. After doing this, go to your gameinfo folder and open the files for the ships you want to change with notepad, go through it till you find the resource costs and change them (note that phase is Vasari, psi is Advent and tech is TEC).
If you need more details just say so 
