The last 2 years that we went, I made 2 one-way reservations at Dollar (one to get from the airport to the resort and one to get back to the airport from the resort). We were staying more than a week each time, and planned to use Disney transportation for everything except getting to/from the airport. There were only two of us, so we were able to get a compact car and it cost about $31 (each way, including all taxes and fees)
and if you take the toll road, youll pay another $2 each way for that, so it cost us a total of $66 roundtrip (from MCO). I dont know if they have a rental desk at Sanford.
The best deal for our needs was from Dollar, they were running a special (the same that they are still running, compact for $27.99). Dollar had a rental counter at the Downtown Disney Courtyard by Marriott, and that is where we dropped off the car (and picked up a car for the return trip). As far as dropping off the car, they have a drop box for the keys if you drop it off after hours (and on after hours drop offs, you are on your own for transportation back to your hotel). Youll need to plan on picking a car up during their regular business hours. From that location, we just walked over to Downtown Disney and used Disney transportation back to the resort. Apparently the Courtyard no longer owns that hotel (I think it is Holiday Inn now?), so I dont know if Dollar still has a counter there, but a number of the hotels have rental counters and most have shuttle transportation to get you back to your hotel.
Another option you might check out (depending on how much luggage you have) is LYNX. I havent used LYNX (the public bus), but some people have (from MCO). According to this link;
http://www.golynx.com/?pid=1155688 they also service Sanford.
