When I'm a towing a boat I use a large sainsburies orange 30 p carrier bag as the prop bag with a sheet of wood inside to protect the world from the prop. I tie wrap this on to the leg and it works fine.
I also take my spark plugs to a motorbike shop for cheaper replacements and my filters to a motor factors for replacement Gotta be a good make Fleetguard, Mann or Fram. This usuallly works out at a third to half the price which means I can buy more fuel for Ribbing.
On my commerciall boat I just bought a spare hydraulic valve assemply from Parker hydraulics for 325 poonds as opposed to the 971 that Hamilton wanted. This is not an equivalent or pattern part but the actual unit.
Theres a prize for any good suggestions of 6 mega tie wraps as used by Nasher, Pete7 and David Manning and the best suggestion gets a set of crimps with a proper ratchet crimper plus a night out with David Manning, 2nd prize is 2 nights out with DM and trust me you don't want to come tenth