I've never heard of ShareGrid.

You didn't say what prices you were finding. Below are what I found at some of the well established and trustworthy dealers.

Canon 80D can be bought new at B&H Photo for $1100. A better deal there is 80D with EF 18-135mm f/3.5-5.6 IS USM for just $50 more. That lens normally sells for $600 when bought separately. It's the "premium" kit lens for Canon APS-C cameras.

IMPORTANT: All the new 80D at B&H are "Imported", which means they are gray market, so won't have a factory warranty. B&H offers a "store warranty" and is pretty reliable about making good, should there be any problems (which is rare).

B&H has also got used 80D for $710, body only or for $920 with the EF 18-135mm.

Adorama doesn't have any new 80D, but do have a half dozen used ones in very good to excellent condition, priced from $549 to $599.

MPB.com has 25 80D bodies from $609 to $639, depending upon condition and "mileage". One nice thing about MPB is they list how many shutter actuations the cameras have done. The 80D is rated to do 100,000 clicks, so some of the low mileage ones there have a whole lot of life left in them.

UsedPhotoPro.com (Roberts Camera) has four 80D bodies available used, ranging from $570 to $657, depending upon condition.

KEH.com surprisingly doesn't have any 80D right now.

They're out of stock at Canon USA Refurbished, too. The last price on them there was $719 body only or $719 with an EF 18-55mm STM lens (the more basic kit lens).