Are you the type of player who likes to stay back and take precision shots versus running in and gunning? Do you like sneaking around and utilizing cover to make shots from concealment? Do you like playing more of a scouting/observer role so that you can support your team? If you answered yes to any of these questions, perhaps airsoft sniping is for you.
Sniping in airsoft is a fun way to mix it up a bit if you've already been playing as a rifleman and certainly an inexpensive way to start given the nature of the rifles themselves. Most airsoft sniper rifles are spring powered. This keeps the cost to get into these rifles very inexpensive to purchase and to operate. Spring powered sniper rifles are much like spring pistols, just much larger and more powerful. Before firing a shot the bolt must be pulled back and cocked, like a real bolt action sniper rifle. Most good quality sniper rifles will shoot at least 400fps or more, which gives you an edge over a stock AEG. With the added power you do gain a slight edge in range too. But because these spring powered rifles do require some arm strength to manipulate the bolt and pull back to cock the rifle, this type of airsoft gun is not ideal for very young players. A type that might be preferable for younger players would be gas powered. This is a small category and there are not too many rifles of this type available, but they do cost more to use in the long run since you have to buy propellant such as CO2 or green gas to use them. But with these you do not have to fight a heavy spring to cock the gun.
You should know that when you purchase an airsoft sniper rifle, many of them will not come with any sights for aiming. It is assumed that you will pick up a scope of your choice and add it to the rifle you end up with, so often times you will just have a rail on the gun and nothing more. Another tactical accessory that you may want to consider to go with your sniper rifle is a bipod if your rifle can mount it.
Another consideration is heavyweight BBs to squeeze more accuracy out of a stock rifle. Heavy BBs are less susceptible to wind deflection and will keep a straighter flight compared to a lower weight BB which can veer off course very easily.
Sniper rifles start at under $100 and can go up significantly in price. What should be your deciding factor for buying a sniper rifle is what your priorities are. Most of these will shoot around the same velocity (~400+ fps or more), but the difference is the build quality and how solid the rifle feels. The cheaper rifles will feel light and more toy-like, but will shoot identically to the more expensive rifles. The more expensive rifles will have more metal content and weight, nicer stocks, and potential for upgrades down the line.