"He who marches out of step hears another drum." ~ Ken Kesey
Have heard many ideas for equipment with 10 year or so life expectancy : -check the trade classifieds and see what they are listing like equipment for-1 year old, deduct 25% -- 2 year old, deduct an additional 10%-- for every year after deduct an additional 5%. If this is obvious please excuse me - but if being done for business/legal reasons- always like to get professional advice.