Kenma will charge a surcharge, (was $40 not sure now) to supply a rack without a bag. If you look at your ventura bag you will see three partitions marked on it so that one bag can be used three times to buy a rack.(really old bags won't have this ) If you order a rack without the bag they even supply the envelope for the tag to be sent back in. One of the ways around this is to order a sports rack, or just the side brackets, but then you can't fit your bag on unless you have the back part already. They don't actually have a part number for the kits, they list the items individually. So if you order the side brackets and the back one, to them it's a kit, and you will get charged the surcharge. They are really fussy about it.
The reason they do that is to try to stop people buying oversize bags, ie. the Rjays explorer bag which can carry a lot more, and overloading the rack and breaking it.
Gearsack went out of business years ago..

Mohawk miss I bet if you look at your kenma invoices you will see the surcharge on there.