Lots of threads on this. It’s very easy to stay under $500 and outfit yourself for anything you will encounter cleaning storefronts.
Pole: 10 foot or thereabouts.
Squeegee: 18" (recommend Ettore brass with Ledge-Eze handle)
Strip washer: 18" sleeve on a swivel T-bar (recommend Moerman’s sleeve)
Smaller size squeegees and washers are optional, depending on the size of windows you encounter in your area. If you only get one other size, make it 10" and you should be set for almost anything. I personally carry only an 18" squeegee and washer on my belt, but keep a 6" 10" and 14" in my truck just in case.
Any lint-free towels will work for detailing edges. Lots of guys like surgical towels. I personally prefer scrim and do fine owning just 3. One scrim can last all day. You can even use old bath towels as long as they don’t leave any fibers on the glass after wiping. Microfiber isn’t the best, unless you plan to use then for actively scrubbing instead of just picking up drips.
(3) 5-gallon buckets w/gamma lids. One for water, one to keep dry towels in, and one to stow your wet towels and tools.
Dawn 2x or 3x work well for cleaning solution
Belt and squeegee holsters and other doodads are optional, but can save you bending over a bazillion times a day or making trips back to the truck.
I’d estimate something like 99% of all storefronts can be cleaned with less than $200 of equipment
