I'm building a 75A J-1772 OpenEVSE, this way it will be able to charge any vehicle, my total cost will be about $550.00-$600.00, so the price of the portable UMC cable, with the capabilities of the WHPC.
(just bought and received the 75A ITT J-1772 connector/cable on eBay for $250, the 75A contactor I have found a source for $120, those 2 parts are the bulk of the total build cost), the case is also a little pricey too (~80)
I also installed (2) 14-50Rs off the garages 125A subpanel. Both 14-50s and the 75A J-1772 can be used at once, because OpenEVSE is now adjustable for the current setting via a 1-button menu system, so the current availble can be dialed down to whatever you want, from say 12A to the full 75A... Once the "sweet spot" for charging is discovered. you can also adjust it in the car (for a lower number than the EVSE advertises), but this is just one more way to adjust it, and even allow both 14-50s and the J-1772 to all be used at once (as long as you stay below 125A max total). The 75A J-1772 probably won't be used at full power capability most of the time, it's just nice to be able to "dial in" whatever is need up to 75A, if a visiting Model S/X happens to need a charge, for example. The 14-50s are backups, and for a 2nd EV in the future.
Here is an example of a 75A OpenEVSE:
http://code.google.com/p/open-evse/wiki/EVSE_Example75A
Here is the OpenEVSE homepage, you can see some of the menus:
http://code.google.com/p/open-evse/
Enclosure I am think of using:
NBE-10563 Bud Industries | 377-1146-ND | DigiKey
Has a clear cover, and an "inner mounting panel" (to mount the LCD display to, as well as the "select" switch to adjust the menus), it also has a bottom interior mounting plate availble, so you don't need to punch extra holes in it, and it can stay waterproof.
Enclosure mfr:
NEMA Boxes - UL/NEMA/IEC NBE Series | BudInd
PDF of enclosure:
http://www.budind.com/pdf/hb10543.pdf
75A contactor:
SuperBreakers.netSquare D
Mitch