I would expect a hit on prices as soon as peoples starting to realize they will not do better using UL LP100 instead of buying again and again a limited LP120 perfected. Using a full TT limited LP120 perfected would save you the price of the gun itself.
(math part 470k cycle + 230k on mayhm L amp = 700k, with even the cheap 20% extender 840k cycle, i assume both will be amped with L mayhem and effi diff remains about the same, so 840k cycle with 11% effi diff 6468 ped saved by effi)
We are not there yet, but after some ammount of refills, if they became more commonly available, that 6.5k ped price is not impossible.
Than i see no reason to invest a lot of ped into an UL gun, if a limited gun can do the same end result without any risk of investment.
Might high tier ones will keep their value, i have no idea how fast these new L guns will tier up with normal TIR.
Availability is a big questionmark yet for the LP120 perfected, but i would be worried for my investment if i would own an lp100 atm.