Looks like his prices are half, or less than half of Boardsort's. I would sell him your junk, anything that is not profitable to ship. You may want to check local yards for prices as well.
I've been shipping from southern New England using FedEx Ground. I ship a mix of lower grade materials (peripherals) and higher grade materials to bring the value to $140 or better, while shooting for a weight of 40-50+ lbs. That way, I pay ~30+ for shipping, and still net at least $100 per shipment.
I realize your shipping rates will likely be higher from CA. You can check FedEx rates here
https://www.fedex.com/ratefinder/home. Be sure to click the "drop-off" option, and use "your own packaging". Keep in mind that packages over a certain size will have an OS surcharge.