It's a standard 2.75 inch FFAR, Folding Fin Aircraft Rocket. The motor is old, and the old color code (now they are White with a brown band), and appears to have been made in 55. The gray motors are scarce, but not impossible to find. It has a 6.5 Lb. plaster filled practice warhead ( the smallest warhead made), and the fin set is from a loading dummy. There might be a lot number on the fin blades. It is missing the lead lock ring that holds the fin assembly in, so you can grab the fins, and work it back and forth, and pull the whole fin assembly out if you wish.
The Longbow Apache fires a longer Mk. 66 motor with warheads in the 17 Lb. range.
As you know ordnance prices are all over the place. Someone might pay $500.00 for it, but they usually sell in the $150.00 range, maybe a little more for a Gray motor.