I spend a lot of money on gear, but I wouldn't go into long term debt for anything. Ever.
I've managed to avoid all debt so far in my life, and it's a great thing. Typically people my age have student loan debts, or (worse) credit card debts (something I'll just never understand).
Sometimes I will go into temporary debt, balanced in my head. For example, I'll spend a $1000 on a great opportunity for a bass (maybe it's rare, or priced to move fast). I know I'll be getting $500 next week, and I have $500 in my savings account (for example), so I go ahead and get the bass, knowing that I will have it payed off within the week.
The analogy I always use is a river: people who live pay cheque to pay cheque have a cash flow like a shallow river: it's a steady trickle, but there's not much of it.
Myself, I have the same flow as anyone, but my savings account means that my stream is much, much deeper, and I can dig in and buy something expensive, knowing that my flow will slowly fill it back up (at which point I can buy another expensive thing

). Going into debt is sort of like damming your river: suddenly you have a pool of money, but on the other side, you're down to almost nothing for a long time down river, trying to pay that debt off.