That is up to YOU, would you be comfortable fitting the board in a N64 cartridge shell? With Stonage you are paying for the excellent work put into the packaging and shell etc, if you are comfortable doing it yourself you may save a little bit.
I've ordered all my Everdrives (I own them all, except the Super Everdrive) from Retrogate. Shipping is cheap and has always been fairly quick. He offers shells with most of the carts, so you don't need to find one separately.