From what I recall, Phil only has the smaller toolboxes like the ones on the Mach 1. hey won't work without modding the frame brackets and even then there's no air filter on this style. Bevel Heaven and Domiracer won't have anything like this and I've never seen them for sale at any other vendor.
Best bet is eBay. I've seen them show up there and have even bought and sold a pair there myself.
OP hasn't been back since posting his query so I'm wondering if it matters anyway...