Depends on where you live, I'm just gonna assume you're from the US. You pay with your credit card. I buy a gun to protect myself. I think it's worth it, it's the greatest weapon ever made and easily accessible. I think you'd be a fool to not own one.
Buy an ar15 first. What's your budget? I'll let you know which to get. Next buy some 30 round pmags, here's the link
https://magpul.com/pmag-30-ar-m4-gen-m3.html?mp_global_color=118 Get some 223 ammo to train with and some 556 for actual application.
Next you can buy a pistol, you sound like you're looking at a glock. Get a glock 19 or a 26 if you want something concealable and get a glock 34 if you don't care how big it is and want the most accuracy.
Buy 9mm hollow points, they expand causing more damage to people. Also get a good holster. It's 100% worthwhile.