Well, I’m pretty sure that you got ripped off, at least a little. The Primo version is newer than the Burly though. The kits I’ve seen on eBay (Before they get taken down for IP infringement) are generally as expensive, if not more expensive than buying directly from V1, and do not support the development of the product.
For the size, look on the parts, they will be marked with a “C”, “J”, or “F”
C is for Conduit, and works with 23.5mm OD (3/4" nominal) electrical conduit, commonly available in North America at big box stores.
J is for Jumbo, and fits 25,4mm (1" tube) structural tubing, either mild or stainless steel.
F is for Foreign and fits 25mm structural tube, generally available in countries that have converted completely to the metric system, ie: the world outside of North America.
The letters will be marked on most of the supplied plastic parts.