Welcome!
If you're new to the sport (assuming so as you haven't mentioned playing yet) I advise renting for a bit to make sure it's something you enjoy before spending silly money. That goes for both buying gear and recording equipment. If you plan on recording for your own amusement and to a small audience you don't need 3 cameras, but I would say 2 is the bare minimum: a headcam and guncam. You'll need some decent editing software too. I use Sony Vegas Pro 11 for any YouTube content, as well as Audition for audio.
Selfie cam - set it on the end of your gun, preferably on the side.
Scope cam - ideally placed on the top of the receiver/handguard/scope. Wherever you can fit it without hindering your sights.
Helmet cam - Some stick it on the sides of helmets, but reversing a gopro style camera and then flipping the video in post gives the best POV.
It won't be cheap. If you're going to start uploading content you'll want some decent quality cameras and put the effort in to make sure it's something people are going to want to watch. It doesn't have to be 4k, but 1080p would be a good starting point. A few to consider are the GoPro Hero series, Runcam 2, Contour Roam series and the Mobius Action Camera. Sure you might be able to find some decent cheap ones such as the YI Action Camera but you'll most likely sacrifice a lot of the quality - visual and audio - in the process if you don't pick right.
You'll have to buy mounts and even housing cases to protect the camera in some cases. Brain Exploder make 3d printed ones if you can't find any for the camera you're looking for but they're pretty pricey for a bit of plastic.
@Samurai might be able to help too, as he owns a 3d printer. Lens protectors to make sure you don't get your fancy cameras broken within the first 5 minutes is equally important.
Memory Cards. A 64GB per camera should do the trick as long as you remember to switch them off on breaks! Batteries are also required. You'll need multiple per camera if you play for an entire day. You can get charging packs which will prolong the life. Very useful to have one on the back of your lid.
Then if you've got all that you'll need the content. A fair few Airsoft YouTubers have quit producing content because they have to completely change up their playstyle in order to get good footage and ended up prioritizing it over having fun. Killed the game for them.
At the end of the day you're looking at spending at least a few hundred quid for the setup you have in mind, in addition to whatever editing software you choose (unless you pirate it).
Not to put you off at all but there's a lot of parameters you need to consider. It's not just 'stick a camera on the end of your gun and upload in bulk'. Good for perhaps yourself, but not if you want any sort of audience.
