here's a build i did for around $58
liquid tight fitting $2
ball valve $7
s/s hose $4
1/4 square head plug $2
brass hose barb $3
i didn't take a picture with the hose barb attached. Also the handle touches the cooler, but fully closes an extension would resolve that. I ended up buying two s/s hoses because the first one wasn't s/s it was plastic tha looked like s/s.
Home Dept cooler
1/2 in. brass ball valve.
Can lift on the valve with a full 10 gal.
S/S house braid attached with zip tie and 1/4 square head plug.
Parts assembled. (washers up top are not part of this build.)
1/2 thread. I used some pipe tape on them before attaching ball valve