Materials:
Neoprene - easy to repair (aquaseal) but variations in buoyancy from the compression of the material at depth are one disadvantage. Neoprene is one of the cheapest suts to manufacture.
Crushed neoprene - DUI created a system that uses a thicker piece of neoprene and by putting it under great pressure permanantly crushes the material giving a more consistant thickness even with depth variations (pretty expensive though)
Nylon - nylon shells are a little more complicated to repair because the material is not always smooth and does not absorb the glue as readily. They are usually less forgiving of brushes with sharp objects and can cause smaller pinching suit squeeze. These suits can be some of the cheapest depending on intended use, taping of seams, and backing materials used
Rubber - very easy to repair (bicycle tire patch kits can be used) and very durable. The suits generally do not offer much in the way of stretch (flexibility) but quality suits are available for less than $1000. Viking has a newer rubber material that does stretch, it uses a more flexible backing fabric
Other factors affecting price are:
Brand names and reputations
construction costs, custom fitting, wider variety of sizes, taping and glueing of seams, accessory items on suits, entry configuration, types of seals. (not all manufactures offer all these features but some are very nearly mandatory)
Boots or booties
pockets
One great option we have available now is the DUI demo days were you can try a variety of suits helping to decide on a style. Dive clubs and larger groups are also good places to get opinions and perhaps a dive in a borrowed suit. Finding a store that will rent a suit to try would be great but you may be able to take a dry-suit diving course that will allow you to demo a suit as well...
Tough choice especially when some suits are running over $2000... big investment to consider...
On the plus side they are pretty easy to sell used if you decide on another style and if considering purchase look for a used suit to save a buck or two as well...
Worst case senario repair (all seals, leak check, and leak repair can be done for less than $200 so figure it into the used price if unsure about the suit integrity) The ziper is pretty important to inspect well as some entry styles must be sent to the manufacturer for replacment...
Good Luck!!!
Jeff Lane