I was considering the same thing. Ended up spending a half hour in the plumbing aisle at HD to get the stuff needed for a cooler MLT setup. I went with brass for the MLT because they didn't have any of the SS stuff. Still couldn't find the SS Washers (someone on the forum helped me with that). Then had to go to Lowes to get the ONE piece they didn't have, so that was another 20 minutes. Still not sure I got all of the right stuff. Definitely not the correct o-rings, but it'll do for now.
When it came time to get my kettle stuff, I went right to Bargain Fittings and got the $26 ss valve with barbed coupler. It arrived in just a few days. SO much easier!
There are a LOT of things you can DIY, but I believe things like this should be better left to the guys who have put in the time sourcing quality pieces and troubleshooting.