Search:

For it to meet service class, changing the grip to an A2 grip, and the stock to a M4 Carbine stock should get it into Service class.
...and having a fixed optic of no more than 4x.

My guestimate...

I have a few ST AR's and a Mega, and assuming the upper is all spikes, my guestimate would be around ~$2400 new, excluding the scope & mount.
That's based of the basic rifle worth ~$1900+ adding the...