I buy the units directly from Volante in Korea, he ships worldwide. The G34 (black) hasn't had many rounds through so it wouldn't be a meaningful indication, however, the TTI style one as seen in the video has had many more, close to a thousand if not more given it's the go-to for the IPSC style shooting I do until recently, this slide made by Trigger Happy has slightly different fitting to normal Guarder slide so I suspect the barrel / slide contact is not the same as the Guarder ones, the TiN coating has worn / chipped at the corner where they meet, but otherwise it's held up well, there's zero wear further down the barrel near the muzzle / slide contact.
I'm also using real sights for both the G34s, while Guarder advertise them to take RS sights, they actually don't, not without different modifications, the cuts are wider than the real ones so you'd have to either pack them out with materials (aluminium sheets or card), or in case of the TTI slide, which uses traditional TM design so I used an imperial countersunk screw to pull the rs sight down from under the BBU at the hole designed for grub screw. As for price of rs sights, you can get a set of steel made fibre optic sights for Glock (the one seen on the Guarder black slide) from Amazon UK for £26. Feel free to PM me if you want more specific info for your builds etc.