BMS Per-Cell Cost?

What are people generally paying, per-cell, for a system which includes:

  • Charging
  • Protections (overcurrent, under-voltage, etc)
  • Active balancing

I’m curious about off-the-shelf systems vs DIY.

For systems based on 18650’s or 26650’s.

Not counting the cost of the cells, cell enclosures, wiring, etc. Just the circuitry.