Very interesting idea, glad I caught your post.
I graduated from Auto Mechanics, and here is my take:
Lease a white GMC van with no windows, and literally research Blue Point level quality of tools, and find distributors to buy them cheap.
If I wanted to take the risks of running around, I would load a truck with tools I got on sale, say, Mastercraft Maximum tools.
Lisle stuff, Ingersoll rand, solid wrenches and specialty stuff that people buy when they are desperate...
Have a run of nice business cards done with your cell number.
Make a list of All the local tire shops and independents, and make a presence all the time and say hi.
If a mechanic is desperate for a tool, be the Johnny on the Spot... Even pick up a tool along the way if you don't stock it.
Have some chips, a cooler with drinks, some twinkies etc...
You will run around the same, but the risks are FAR less than getting involved with Snap-ON.
These guys just need a solid tool, you can do cash deals and make trades, with Snap On you can't.
You bump into a few Tire Season kids needing an impact, an IR here and an IR there because they are new on the job... $$$
I would never sign up with Snap On. Be your own small business instead, take much fewer risk in this instance, but stand to massively gain.
And, down the road, if you are a success, Snap On will gladly sign you up if you choose.
If you are a mover and a shaker, you will succeed with your own truck and your own quality stuff.
The key is to be on the road working it all the time, and listening to client needs, and stocking it.
Also as mentioned, if they are desperate for a "good" tool, and you are inexpensive, you can only make cash on the spot sales. They can borrow 20$ for a tool from a buddy.
No chasing people then if the tools are just affordable. People want the service. They want the tool and they need it now, that is the business model they need.