Price varies a lot, nearly as much as quality.
If you intend on keeping the bike for a long time, get the best quality you can afford, long time value for sure!
Below is taken from another forum from someone who seems to know his shit.
All the below is written with the trail-rider in mind:)
The only difference b/w a std o-ring and and x-ring (or w-ring or whatever the manufacturer wants to call it) is the o-ring. An o-ring chain has an o-ring but before you say “no shit sherlock!” the x-ring has a flattened o-ring that is essentially one o-ring inside another. This sounds simple and it is but it offers a huge advantage when it comes to keeping crap out and grease in. Does it cost much more? not to make but the manufacturers gouge us for it anyway. Yes they are worth the extra cost but they really should only be $10 dearer (if that) than an o-ring chain. Any x-ring made in Japan will be good quality. As barker has said, the extra friction from the o- or x-ring does rob a few horses but it a compromise that is worth taking.
When it comes to sprockets go steel but there are three manufacturing techniques.
1) stamped. JT make their sprockets this way. It makes sprockets quickly but must use soft steel – both of these keep the cost down. However the die wears quickly and this must be taken into account so they have to cut bigger grooves for the chain than they actually need – this stuffs your chain quickly. You can tell these sprockets as on one side the teeth have a flat edge while the side hit by the stamp has a curved/bevelled edge.
2) Cob Cut. A bundle of blanks is piled up and each groove is cut individiually by a milling machine. This allows a harder steel to be used and a more precise cut. The milling tool still wears so they have to cut a slightly larger groove than really needed to allow for this through a run. Much better than the stamped sprokets though. Renthal and Stealth are made this way.
3) Laser cut. By far the best method and also the most expensive;) A laser cutting tool is used to cut the grooves for the chain from a blank. There is no tool cutting involved so the hardest possible steel can be used. Each sprocket must be cut individually. These two facts push the price up. Because there is no tool wear to account for the teeth are cut the exact size needed for the chain. The hard steel and precision fit gives best possible wear for you chain/sprockets. AFAIK only Chain Gang make sprockets this way.
The advantage of the cob-cut and laser cut sprockets is that you get multiple front sprockets out of a chain and rear sprocket. Watch the front sprocket carefully and as soon as you notice any curling of the teeth whip it out and replace it. With this method you’ll get two fronts for a rear/chain for the cob-cut and three for the laser cut. Use the chain as a guide if you are uncertain of the wear of the chain/sprockets. If you can pull the chain more than half it’s width off the rear sprocket then it’s time to replace the lot.
