Purchased two S models within a week of each other, Nov/Dec 2012.
Mine, an 05 with 100K miles, from a Toyota dealer.
Wife's, an 06 with 28K miles from a local used car dealership.
Paid full retail on both at the time, or at least nowhere near what everyone has posted here.
Close two full retail on both, and was really worried about maintenance. Replaced a right wheel bearing on mine and part of the steering column. PS fan needed to be replaced.
Just took a 2500 miles round trip on mine with zero issues, just under 121K now. Gas mileage was the best ever!
Wife's, replaced all brakes/rotors, (wear sensor came on) and wheels bearings (not needed, just did) and currently has 57K.
They run like champs, and I do worry about the reliability....

 

From my experience, I'd say no. I paid $5500 for an '05 MCS and drove it for 3 days, about 100 miles total. First the tranny went. Put in a rebuilt one and a clutch, $4200. Day after I got it back the PTO/water pump gears went. It's gonna be about $1200 to fix. As it is I've owned the car for 3 months and I've basically only driven it once. Made it out to where I was going, but never made it home.

Maybe mine is an extreme case, but I'll never buy another one, and I'll not recommend an older Mini to anyone unless they want a money-pit. Just my 2¢.