I have to disagree with you last statement Lynne. I've been in Lake Michigan in 42 degree water and the only parts of me that got cold were my fingers and lips.
Suit materials are one of the biggest differences, but not for the reasons being discussed.
The suit material and the "cut" of the suit has a big impact on
- range of motion/comfort
- durability
- drag
- price
Lightweight trilam is by no means even remotely as durable as crushed neoprene or vulcanized rubber. As a general rule, the lighter the suit, the more it will leak. The other side of this coin is that the lighter the suit, the more it costs so (perhaps illogically) the most expensive suits tend to leak the most..... Weird for something called a "dry" suit.
On the other end of the spectrum, heavy materials generally don't offer the same range of motion or comfort as lighter materials. Expensive suits are expensive because they're more comfortable. Cheaper suits tend to be heavier, leak less and are more durable but are less comfortable. This has to do with materials, not price, but there is a correlation.
The third element is drag. A suit that isn't cut well can be really baggy. That's bad if you want to swim efficiently through the water. The Bare nexgen is a good example. Its' dead cheap, leaks a lot (bilam) and drags a lot but it's perfect for rental stock because they're cheap and fit a wide range of people. Neoprene suits also tend to be less draggy on the whole than trilam suits but that depends to a large extent on cut and quality.
Conclusion.... You can't really decide based on price if that suit you're looking at is the right one for you. You have four main elements to balance price, comfort, durability and drag.
drag and comfort are opposed
durability and comfort seem to be opposed
price and durability seem to be opposed
low price and high drag seem correlate
high price and low durability seem to correlate
high price and high comfort seem to correlate
All of this is independent of brand and very general. There are probably exceptions.
R..