The 24-hour-shop and sloppy sets are very rare and therefore often sell for high prices. The Cabana set is hard to obtain but not as much so as the other two, in my opinion.
7-11 set : High demand, worth a whole lot currently
Sloppy set : Not in demand as much as the 7-11 set, but has and will remain very popular, so fairly valuable
Cabana set: Still valuable but easier to obtain and less popular than the other 2. Still fairly valuable though