I keep checking rates for renting a minivan from MCO for a week in August (16th-23rd) and the best deal I've found by far is on the Costco Travel site. $288, all fees included, extra driver included. Through Enterprise. It is also easy to cancel. I will keep checking all the sites, but I don't see how I can get it lower than that, especially with the extra driver included. If I figure it out the daily rate the way all the car rental sites do (pre taxes and fees) then I am paying $31.06 a day. After taxes/fees I am paying $41.14 a day. A quick scan of prices today shows me the lowest price per day, before taxes/fees, is $48 a day.
While I would strongly prefer to rent for only a few days from the Disney Car Care Center, it is at least $200 less than any other rates I can find anywhere for a minivan to rent at MCO for the week.
While you can check the prices online on their site, you do need a Costco membership to actually make a reservation - the yearly membership fee costs $55.
I wish that we could do the Drive Happy deal - we have 5 very tall adults and me, the short adult. We need a minivan. Sigh.