Submitted by Devilfox
There are couple other options I found.
One is on a website called Supply Captain, they have a 'DUAL HYDRATION SYSTEM/PRC 119F RADIO CARRYING POUCH' that can carry an ASIP. Price is tad steep however, $129 or so. But can carry few other things too.
Second option in on the website, Kifaru.net. They carry a 'Radio Pouch' that hangs internally for the older 119s. I am sure if you contact them and ask, they can adjust the width. Price is a lot more reasonable around $29. Only catch is, it's an internal mount-on backpack. Which, honestly, in the course of things ain't too bad.
ED - Devil, I like the look of the SC dual hydration system, especially the fact that you can wear it as a stand alone pack or you can lace it in to something else (another pack, the back of your IBA, what ever is MOLLE compatable.) I'd consider it for that feature alone, and just lace the thing to my IBA, but I haven't ever served in a unit yet that let you take your IBA off (except when you were asleep) and packing a radio and ammo into the porta-john gets old, so all my kit is still on the RACK. On the down side, though, as you said, it is a little pricy, and for that amount of money I could get a full blown assault pack. I would certainly consider this over the S.T.R.I.K.E. ASIP pouch though, even though it is more expensive.As for the Kifaru radio pouch, as you said, the pouch they offer is basically an internal radio hanger for ruck sack sized packs. I already have an assault pack that both the full sized radio, or a pair of ASIPs will fit into, and my ruck (a CFP-90) comes with a built in radio bag. Again, of the two, even though the Kifaru is cheaper, I'd go with the Supply captain bag.