Remember these are just prices, they do not reflect the ability of a rider. I know plenty of really good riders who like to ride around on entry level boards because of how soft and flexible they are. On the same note I see many people who aren't that good at snowboarding yet, ride around on some of the most expensive boards. 

The snowboard buyers guide:

If the board falls anywhere between your collar bone and your chin, it is considered a short board or a jibbing board. Remember boards can't tell how tall you are, they only react to how much you weight. So a short board would be recommended for a lighter person because they are small, light, and easier to make turns with. There is nothing worst than trying to turn a really big board when you are a tiny person. You will end up hating snowboarding if you are in that situation.

The easiest way to measure this is to strap or step into your bindings. Then hold the board up at one end at a time and look to see if the toe or heel of your boot goes over the edges of your board. If they don't then you are good, if they do then you might want to consider looking for a wider board. Having toe or heel drag will make your toe's or heel's drag in the snow during your turns. You will not be able to make perfect turns, plus you will probably wipeout a lot. Having your toes and heels placed over edges will give you the proper control over the board.

The torsional flex is how much a board flex's from side to side. The more flex the easier it will be to turn. Too little flex and the board will be hard to stay on edge during a turn. The longitudinal flex is how flexible the board is from tip to tail. A balanced flex is what you want. You DON'T want a board that has a different flex in the nose then in the tail or vice versa because it will cause an uneven flow between your turns. A softer flex board is good for beginners and jibbers because they are easier to turn and they are more forgiving. A firmer flex board is good for racers or carvers.

The sidecut is the area between your edges and the top of your board. Ashallow sidecut is good for longer sweeping turns. All mountain boards have shallow sidecuts, they are easier to control. A deeper sidecut is easier and faster to turn. They are good for beginners and jibbers.

twin tip snowboard

directional snowboard

rocker snowboards

flat snowboards

camber snowboards