I didn't see quantity on the page you posted but for that price I hope they're getting more than 5!! That's a ridiculous price for these units, I've seen them some other places online and they go for <50 K fully equipped. Of course if they were sole-source which it appears they are the seller can jack the price up.
I imagine they are being purchased mainly for use at special events because they are much smaller and can be maneuvered around people and equipment much easier than a large ambulance. I don't think there are enough places in NYC that would require the all-terrain capabilities on a regular basis.