there are a lot of options for 7 or 8 windows and under 26k.. its tough to just name a manufacturer though as for instance my 7 window carpenter is 27,500, I saw an 8 window IC on a site recently that was 22000, my 6 window bluebird is 17,500...
most of the auction and sale sites will have the GVWR listed..
depending on your state you may be limited in registration to the RATED Seating capacity as well..
for instance in OHIO Capacity is measured in GVWR and FITTED seats.. so my redbyrd at 17,500 with only 14 seats is considered a standard passenger non CDL vehicle...
in MICHIGAN they go on RATED seating so if the bus was built and rated to seat 32 people, you could have all the seats out and its still going to be a CDL vehicle because of its rating..
check your own state..
MOST STATES you DO not require CDL if you re-title it and register it as a Motor-home regardless of GVWR and number of rated or fitted seats..