Ok, I am going to be harsh-Mom type advice.
If YOU don't have the money, then you are asking SOMEBODY else, (whether Freind , parent or credit card company) to buy you something, and you are promising to pay them back. But honestly, you are not buying. Not investing. Not carrying your own. This, for a hobby, can bleach the fun out of it.
If you can't pay it off every month, in full, credit cards are, in my opinion, a "Downward rip current on Nitrox"
I am trying to raise money for a dry suit, I have my dining room furniture on Craigslist and my kids old Lego toys and my best jewelry on EBAY. The only bid I got day one was for a 40 year old half-the-parts-missing-Lego kit. You Frickin' never know how your going to raise cash, but if I cant raise cash beforehand, I know I will be LESS likely to raise cash when I am diving with my newly aquired gear. I'll be too busy!
Rant over.