SC does  understand the higher fee for sending docs. back and as they recommended to me & have found it to be true--sending them back priorty mail thru the regular post office (you get a tracking #) is the least costly way.  You can put as many pages as you can fit in the one big envelope for a flat fee.  Just be sure each document is numbered properly w/their order & loan #s.  Now if you had a ton of requests, I don't know if USPS would suffice.  But when I called around for prices, the post office was the cheapest and I haven't had a problem w/them delivering.  Also, SC pays for the certification cost.