Creatine is not a hormone so there is no need to worry about stable blood hormone levels or anything like that. You do not need to supplement with it daily.
If you are trying to save money, you can take the creatine only on workout days, that is perfectly fine.
Just an FYI though - a creatine supplement shouldn't be expensive. I use ancient strength from n2bm.com. A 30 day supply is only $15. I use 3 capsules (5g) each day.