Hmm. How do you get the tubes connected without the torque (is that the correct term?) twisting the tubes all over? I've handled the typical gasmask tube and they don't respond to twisting well. I'd think it would be around 15-20 dollars for a pair? Maybe you can get the end sockets separately from someone.

The ends spin freely, allowing the tube to not have to twist, and it seals once it is tightened.

the hoses are definitely hard to find, making the wye itself is Much easier to do!

Hmm. FortTroff.com, a gay fetish supplier sells the hoses for 9.90 each.
There's a couple other places that do so I think. eBay maybe.
I've never seen one of those connectors that spins before. Good job!

I've run into them before, last time I needed them in a rush for a mask order and thats when I found them. Comes to about $13 after shipping. x2=26, (as I need two of one connector and one of the other, and each hose only has one of each) plus the extra $15 of work and materials I put in to making the wye, comes to about $40 for one fully assembled wye.

I've looked online for premade rubber wyes, none exist.