Upholstery - Re-cover foam boxes

We have foam boxes in our gym - they are used for box jumps - see pic attached.

They are covered with a robust black vinyl - this sort of thing: https://www.iwantfabric.com/uv-resistant-waterproof-pvc-vinyl-cover-fabric.html

The covers are now old and have ripped so we are looking to get them re-covered.

The boxes are covered on all 6 sides - they can be used any way up, there is no "top" or "bottom". They need a zip fastening on 3 sides to easily get new covers on.
They need to be as robust as possible, they are for jumping on but get picked up and thrown around a lot - perhaps both sewn AND glued, but I'm no expert so open to ideas!

Dimensions:
18x24x30 inches

We are looking to order 8 replacement covers minimum - we may increase this depending on price. Please quote a fixed amount for 8 covers plus an amount per cover over that.

Please quote for both labour AND materials.