$17k AC + Furnace Installed – Other Options?

New to Houston so don't have many contacts. My house needs a new 5 Ton AC plus furnace (actually that is questionable…). I was quoted $17k for a two-stage Lennox, includes AC unit, furnace, plenums – basically everything but new ducts.

Is that crazy? Ballpark reasonable? Other contactors y'all suggest?

TIA!