In addition to being complete overkill for a 9600, the VGA Silencer has been out of production for quite awhile, so it's difficult to find one, and when they do come up for sale they tend to be priced for as much as the AIW 9600XT is worth. Plus not all revisions of it fit the AIW cards. (And the 'ATI Silencer' that replaced it definitely doesn't fit them.)
Those cheap 'flower' type coolers are more than sufficient for a 9600XT. They're even fine for 9700/9800 cards, and a lot of the modern mid-range cards too... I'd say pretty much any card that's low enough wattage to not require the auxiliary PCIe power connector. I've used a few of them myself, they're certainly not the greatest thing ever made, but they're hard to beat for $5 shipped, and they work better than a lot of the stock coolers on these older cards.
It may require bending or clipping a couple of the fins to get it to clear the tuner shield box on an AIW card, but it shouldn't be too difficult to make it work.