My advice - make kit decisions after the course, you'll save money from making purchase mistakes.
If after the course you're struggling to find funds to purchase additional kit e.g. stages etc... ask around to see if you can borrow a stage or two, or pair up with someone on a dive that can lend you kit it need be.
In my opinion if you can't afford the right kit for the dive - don't do the dive.
Hope that helps
G