Why you against Dealership ?
I live in a Suburb outside of our major City and have three choices for Jet Ski repair all only 7 minutes from my house and at least four other repairers about 20 minutes away, I would think in a large city like Chicago, you would have a lot more choices.
I prefer my Dealer as he is either the same price or cheaper than the other two and they have the correct Oils and filters as the other two would have to buy the parts from the Dealer any way and pass on the added extra ?
I also look at reviews from other people that have used each repairer and all three are a good choice.
Warranty wise though my Dealer gives me the best deal.
Where I live it's $300 for a Service, it's the same price at all three
I used Google, it's a search engine on the PC or also on Smart phones, if you put in the search bar Jet Ski mechanics in my area, it will list all available choices and lists them in distance from you, if you have location enabled.
in many cases parts for skis made before 2006 are no longer available. At my shop I do not even accept skis as old as 2004 for service as very often the parts I need to make the repair are no longer available and the customers put the blame on me, and then do not want to pay for anything I did up to the point of running into the unobtainable part. At this time I rarely take any skis made before 2010. Its just not cost effective for me to try to track down parts on ebay or other salvage sources. Who will pay me for that time?