Sure they do..."A cheap technical diver jumps in the water with only about $7000 worth of gear on."
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a regulator is NOT a good place to be cheap.....(snip).....without making too many generalizations, you are not going to find a cheap regulator that is also good in cold/dirty conditions. Environmental Sealing a reg gernally cost money, often on the order of $100-250 more. Also the sealing generally limits the overall performance of the reg, although most are so good the loss is neglible.....(snip)...Your regulator should be the absolute best that you can afford.
Once again we get the classic line, spend as much as you can, Isn't your life worth it?
I guess my life isn't worth much. I spent $84 on my go-to primary doubles reg, and about $60 on my current favorite single tank reg.
There is a tremendous amount of hype and BS in regulator sales. Any decent reg in good condition will work extremely well for recreational diving. A few decades ago, pro divers were routinely making extreme dives on regs that most OW students wouldn't take in a pool today. (Some of those old regs breathe really well, too)
BTW, environmental sealing has NO limiting effect on regulator performance.
+1 for what Matt said. There's no reason to believe that a 600 dollar regulator works better than a 100 dollar regulator purchased off of Ebay. If it's rebuilt, and of high quality, the cost does not matter.