If you are not a frequent player or you are just starting up with BB games you might want to consider cheap bb guns. Although the quality is not that good you will still be able to feel the game and decide if it fits you.
When buying cheap guns there are a few things that you should look for.
The best option for a discounted gun is a spring powered one. This doesn’t mean that spring models are better that the rest. It only means that they are cheaper to make and for the same amount of money you will be getting a better made bb gun.
From the gas powered and AEG models you should only get a cheap bb gun if it has been deeply discounted with something like 40-50 or even 70 %. Those will be most likely older models, but with good quality. For me, the better option would be an AEG as gas powered guns will have bigger maintenance costs involved like money for gas and rubber sealants.
Which ever model you choose you should be aware that cheap bb guns will not last long so be prepared. They might last 3-4 or even 10 days of war games, but they might leave you unarmed even on the first one.