Division sell is operating at full capacity producing component XX2 which it sells externally for $8 per unit. The variable cost of production is $5 per unit. Another internal division, Division buy is negotiating a transfer price for purchasing component XX2 from Division Sell. Because of saved transport costs, the variable cost of producing component XX2 for Division Buy would be $4.50 per unit.

What is the minimum transfer price that Division Sell should accept for transferring component XX2 to Division Buy?