What are the install cost differences in the receptacle vs. wall connector? I did the 14-50 install myself and the biggest cost was the 50ft of 6/3 romex (holy crap is that expensive now), but that wouldn't even cut it for a 60A circuit. True, you don't need a box, receptacle, or cover plate for a HPWC install, but that's what, $15-$20?
OK, itemized invoice time!
1. Breaker. If you're doing the wall connector, you get to use a cheap, standard $20 one. If it's an outlet, code requires a $100 GFCI breaker, so an extra $80 there. I am glad I got mine done back in 2014 before this stupid requirement came around.
($80)
2. Wire. Seems like everybody and their mother-in-law's dog thinks you should do a 14-50 outlet instead of a 6-50. So there is that extra thick conductor for the neutral that is 6 gauge probably for however many feet that goes. The wall connector doesn't require the neutral.
($??)
3. outlet, box, etc. DON'T use a damn Leviton. A decent Cooper, Bryant, or Hubbel one will be about 30-40 dollars just for the outlet. Box and cover plate for an extra $10? Maybe a few bucks shipping too?
($50)
4. UMC plug adapter. Obviously with the hard wired wall connector, you don't need this, so spring for an extra $45 if you want the 14-50 plug or $35 if you want a plug for any other kind of outlet.
($45)
5. Something to hang the cord for the UMC. The wall connector is its own hanger, because you just loop the cable around the body of it, but if you are plugging in the UMC, you will want some kind of hanger or hook mounted on the wall. That doesn't need to be anything fancy, but it is something, even if it's a garden hose hanging bracket. That's another 20 or $25.
($25)
So adding those up, excluding the vague wire cost difference in #2, that is $200 just from items 1, 3, 4, & 5. That wire difference is going to be really variable, depending on how long people's circuits are, so I'm not going to try to guesstimate that one.
I had 125 feet of 6/3 run (actually was between 100 and 125 feet, but I bought 125). Labor ($500), wire, 60A breaker, some conduit ($200), Tesla connector ($500 + Tax). This was June, 2020. AWG 6 is what Tesla specifies for 48A on a 60A circuit.
And because I get nervous when I see this from people, this was wire in conduit instead of Romex? 6 gauge would be OK if that is individual wires in conduit, but not if it's NM-B cable for a 60A circuit.