When you first start playing out you will likely need some kind of PA. The places musicians play when starting out don't usually have PA. Fortunately those are very small places with minimal requirements. Besides, when it's just you, a little system is enough. I know successful artists who still do some acoustic shows and just bring a few powered speakers on stands.
When you get a band you'll likely be playing better shows and you'll have to invest in a PA appropriate to those venues. It turns out that a bunch of places expect the bands to bring their own sound. Or they have a system thats so trashed you can't really used it - and sound good.
So bring your own sound if you want to be presented professionally.
When I first thought about building my recording studio I got some great advice: Build just what you need. Isolated floors and bunker-like walls are great if your in the middle of a noisy city, but out here in the country none of that was necessary. RoughWood Studio was profitable faster because I didn't have to spend so much.
Take the same approach with your PA. Something as simple as stands to get the speakers you already have allows you to do more with less, and use your system longer - till you need a bigger one.
A very wealthy friend once told me never buy the cheapest, and never buy the most expensive. Buy the one just under the most expensive. It's usually the same as the top one anyway, but without some cosmetic feature you don't need.
Also think about weight and space in your van or trailer. You'll be hauling those boxes around. Setting up and tearing down. Even working as a team, you don't want to wear out your guys.
One final thought. If you don't have the money right now, don't buy on credit unless it's 0% interest and you are gigging enough to pay it off well before it comes due. One day over and the interest is just too much. That's how they get you.
So buy just what you really need - not the fanciest - and use 0% interest to your advantage.
It's how much of your hard earned money that you get to actually keep that matters.