I bought a pair of Decibullz which are widely available. Most sellers quote long delivery times though, 2-3 weeks, which suggests none of them carry stock. They're only £25-30 a pair so I don't understand why not.
The instructions said to 'boil water, put it in a mug, drop in an earplug, wait 5 minutes, remove, cool for a minute or two, insert into ear, wait five minutes then remove the earplug "which is now perfectly moulded to your ear shape". Repeat for other ear.' Mine didn't quite go like that........🙄
Boiled water, poured it into mug, dropped in ear plug, waited five minutes, spooned out a blob of molten silicone with the hard plastic bit in the middle, tried to push the flat, runny silicone into something approximating a ball to aid insertion, got close but with half the silicone stuck to the metal spoon (recommended in instructions to prevent sticking), some on my fingers, some still in the mug.
Prodded and poked the now hardening silicone into my ear, realised it was not soft enough, dropped it back into the mug, took it back out, got more stuck to the spoon and my fingers, realised I was down to about 2/3 of the original silicone and that some had blocked the hard plastic canal that should be in the middle but was now offset in what looked like a piece of compressed candy floss.
Tried with the second one, similar result.
Took photos, sent to seller, got a refund.
I'm still searching for something so am keen to see what other answers you get.