I would entertain the DIY kit given the distance. If that doesn’t work, maybe try a septic company with a jetter setup? $600 an hour ($1200 min) seems steep.
Local guy here charged me $425 last spring. I helped even though it was him and another guy. Took a little over an hour. Pouring rain too. He has a 75 hp Kubota diesel on a pump with 250’ of hose.