Use /execute if score:
execute if score @p money matches ..99 run tellraw @p "currency deficiency"
execute if score @p money matches 100.. run tellraw @p "purchase made"
Replace the /tellraws with whatever you need to make your machine work.
I also see that if you have enough money, you're going to want to run multiple commands if the condition passes. Your can either have one check per step:
execute if score @p money matches 100.. run tellraw @p "purchase made"
execute if score @p money matches 100.. run scoreboard players remove @p money 100
Or you can setup a function.