Airsoft guns are a good alternative to paintball. First of all, airsoft guns in general are cheaper. The plastic BBs are cheaper than paint, and they are reusable. Of course the reusability all depends on whether or not you want to meticulously pick BB by BB off the ground. Also, the airsoft gun itself can be cheaper. I bought a new Walter-P22 spring powered airsoft gun for twenty pounds from the forums here. However, this is what suited me. I was looking for a cheap, but still effective gun, so I could participate in airsoft gun “battles.” If you have the money to spend then you could go for spring loaded machine gun type guns. Naturally these machine gun type airsoft guns are more powerful and as a result shoot further. If a power spring loaded machine gun does not suit your fancy, then there is always gas powered airsoft guns. These guns are most expensive, but most powerful. Beside the mechanics behind the gun, the cost also comes from refilling your gas tank which powers the gun.
Once you have the right airsoft gun for you, the benefits keep coming. I do not just like airsoft because it is cheaper than paintball. I like airsoft, because the possible scenarios are limitless. For paintball you have to find a dedicated forest area or speedball court. Though, for airsoft you can go in your house (I suggest basement), any forest, and pretty much any place that you are not openly exposing a gun to the public (you may have some legal issues there). But, all in all airsoft is not messy and therefore the opportunities are greater than paintball.