You could just buy two charm packs, either coordinating or the same, to end up w/ 60 -80.
I would not want to spend time cutting 3 inch strips down. That would be the stuff of nightmare to me. Why not just buy some fat quarters or yardage if you prefer something other than 2.5" ? You can almost always find the yardage of fabrics that are in the pre-cuts if you really want it to match.
RST