I have no experience with this, but I recently had lunch conversation at the top of local So Cal peak with a couple of people that completed the JMT last year. They mentioned using the resupply services of the Mt Williamson Motel in Independence. They highly recommended the place. I have no first hand experience with the place, but the two people I met thought it was a better experience than Muir Trail Ranch.
Here's a
link to their web site. They offer a basic resupply service and something with more "bells & whistles". Might be a little high cost, but sounds like you get a lot.
From the we site:
We also offer our Complete Resupply Package ($150 for one person, $175 double occupancy) that includes:
Receiving and holding one resupply in our secure, air-conditioned facility
One night’s lodging
One breakfast per person
One load of laundry per person
Complimentary ride from Onion Valley Trail Head to motel
Complimentary ride from motel to Onion Valley Trail Head
