"Buy-and-pitch" also sounds very expensive.
I was on the island earlier this month. I rented two chairs and an umbrella from Packlight. Easy-peasy. He charged $55 for... I dunno, probably 11 or 12 days.
We arranged drop-off and pick-up at my convenience, so no need to travel to get the items. Money well spent.
You can take the chairs/umbrella to other beaches (such as Happy Bay or Rouge). Or move further south down Orient, past the yellow umbrellas.
He also rents Igloo coolers - hard-sided, the kind where the top tilts.
Shoot an email to packlightsxm<at>hotmail.com.