Couple of points:
1. Used Speakers in great condition are always the better value.
2. ITU, Dolby, and THX all recommend 3 identical front speakers- So 3 Loudspeakers (Forte II, Heresey, or chorus)- across the front.
3. ITU, Dolby, and THX all recommend that surrounds should be of the same brand /series or just more Forte II, Heresey, chorus..
4. New Klipsch are great.
My best bang for the buck formula would be patient and collect 5 to 7 Heresy speakers of the same version ( I, II, or III) and 2 Klipsch subs ( anyone larger than 12") I have found hundreds of pairs of Heresy I in great condition for less than $200pr and a SW15 sub less that $250- So ~$1100 for a complete killer system?
Purchase 3 Pairs and 2 subwoofers of new Klipsch Speakers and try and stay under 3K.