If you are using a marker or gun as a sniper tool, there are a few things to look for. The best paintball sniper rifle is a pump action gun because these are more accurate and they can hit well at a longer range. Check out
http://www.PaintballDiscountSupply.com for a great selection of cheap sniper guns. It’s essential to keep it well maintained so that the paintball sniper rifle fires smoothly. If it doesn’t, you may have lost your last chance of a hit before you are the one hit.
A Spyder is a good paintball sniper rifle but you should try a few to see which fires smoothly and quickly for you, as well as being accurate over quite a long distance.

A good cheap sniper paintball
gun needs an excellent sight. You need to be accurate with your first shot or otherwise you may not get a second shot, having blown your cover. Snipers don’t shoot from the hip; they take careful aim and try to make the most of every shot, so the better your paintball sniper rifle’s sight is, the better sniper you have a chance at becoming. 

The trigger must be smooth and it must be quick to engage on a paintball sniper rifle. As a sniper, you take your time picking your shots, but once you’ve aimed, you need to be able to fire off quickly before your target moves or discovers you.

So, make sure your paintball sniper rifle is fast and accurate to fire and is dark so it can be easily camouflaged, then get yourself good goggles and decent camouflage gear