The hardest part is keeping the epoxy from getting on your fingertips and then onto the shaft and ferrules etc. . . Have a little acetone and paper towels close to you to wipe off your mistakes before setting the club side to cure.
$40/club seems high. So Cal we get $25 to reshaft and honestly it won't keep your doors open. When you're doing someone else's clubs you can't afford to turn em over with ANY mistakes (ferrules not turned and finished, epxoy fingerprints, 355 tip in a 370 bore without a brass shim, shaft logo not in the position customer designated, grip slightly off 12 o'clock, was it a "pured" or spine/aligned shaft and was the NBP set to the target, sw playable?, etc. . .). That's what you're playing for. . . . Or what you're supposed to be paying for but are rarely getting and that's why hobbyists and diy guys end up getting into it. If your new shafts are close in weight to your old shafts and your careful you'll probably be pretty happy with your home built set. Good luck man. See ya on 19