Easy with Cheat Engine. Put the amount of money that you have in the slot searches for, let 4bits, but make "All" in place of "Exact Value". Throw a research. Buy an accessory, modify the sum of money that you have, and put the result (unique, normally) in the slot of the low. Modify this sum as you want and return to the game.
To your next purchase, you will have the new available sum.