Prices of scrap e-waste for components

If by "wreck for components" you mean extracts parts for use or sale and not disassembly for scrap value then do the following:

Estimate the sale value of whatever you're selling. Price your time and others parts and labor you'll be putting into it. Then subtract the latter from the former. The remainder is the value of the scrap dvd drives or monitors to you. Whether you choose to offer the yard that price is another matter. But that is their value to you.

You can then set the pricing per piece or per pound as you see fit. In general drives are sold per lb and monitors per piece in the ewaste world