It totally depends on where you buy them and how much you are willing to spend obviously. Market prices can get outrageous where at some point it doesn't have anything to do with rarity anymore but the simple economics of supply and demand. Look at German helmets, not really the rarest of them all...yet they go for big prices.
In one sense the Ssh36 should *not* be rare because hundreds of thousands - perhaps millions - were produced in the 1930s and they were widely used by the Soviet armies before and after the introduction of the 'classic' Ssh39/40 model. But most of them were scrapped one way or another, during and after the war, and even before that many - most? - had their original factory liners removed by the troops so that they would fit better over the Ushanka fur caps. So finding one at all is good, finding one with an original liner is remarkable. A simple shell in good condition will sell for hundreds, a complete example could easily sell for best part of 1000 UKP. I'll never have enough money to own one...unless that lottery ticket...
As has been pointed out, by comparision the TR M35 family helmets are common as dirt. But popular, so expensive.
I've read from several sources (not sure if any were an authority or not) that the purpose of the comb was to help "break up and deflect" falling debris so as to lesson the direct vertical impact however, the comb in this helmet is not near as promenent as that of the French Adrians and all its clones.