Not sure I would be able to stomach a $500 service contract on any lawn tractor unless they guaranteed everything and included oil changes for life.
With few exceptions, there is little to nothing on a lawn tractor that going to cost you more than $100 a year in maintenance costs. Most dealers in my area offer a $20 pickup and drop off service for any customer who purchased their mower from them. Several of my current neighbors have mowers who do nothing but put fuel in them and rely on the dealers for everything else. Not one of them has given me a bad report from the various dealers associated with their specific mowers they own. Ariens, John Deere, Cub Cadet and Snapper are what I see them running.
If you are looking for a fuel fill only, not touch mower with included service, I would give Lowes or Sears a chance to explain their service agreements. Lowes offers a 3 year plan for $199.00 that includes door to pick-up and drop-off. The John Deere we are looking at with them is covered for 2 years with 120 hours, but Lowes covers it for everything else, including normal wear & tear. One specific neighbor has relied on this 6 times in the 2 years he has owned his Troy Built mower. Lowes has replaced the transmission 2 or 3 times, the starter & something to do with the deck for him at no cost beyond the initial warranty cost. He said the repairs were completed at a Troy Built dealer, which when I stopped at the local John Deere dealer to considering buying from them or Lowes, their service dept said they do all of Lowes Deere repairs. For a hands free ownership, this is worth considering to me. The John Deere stated they also contact the customer to make sure they don't want regular service performed during the warranty repair, which some may consider a sleazy upsale, but if you are trying to keep your transporting costs down, may be a good time to deal with oil changes and deck/belt adjustments etc.
I personally would buy a minimalist trailer that folds & stands up on a wall next to your mower when stored, possibly even park the mower on it so it is off the ground if you plan to store it outside. Even dragging mulch bags or minor landscaping materials is enough for me to want a garden cart/trailer, but I know that's not for everyone. I have an 8,000 lb skid loader and 3 trailers ranging from a 24' tilt deck to a barely road speed capable utility trailer & a 48' enclosed semi trailer we use for storage at an offsite location, so I am not a good devil's advocate for considering them clutter. I fully appreciate someone's beliefs who feel they are though
