Place To Buy Used Commercial Grade Floor Cleaning Machine?

Have a need for a commercial grade floor machine at our house and am curious – with all of the large scale commercial facilities and distribution centers in and around Houston, is there a 'storefront' that specializes in selling used or refurbished commercial grade floor cleaning machines? I've done some Googling and have checked a few out but curious if anyone here is also aware of a place they'd recommend?

I'm checking Craigslist regularly as well.

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