Just get some cheap anodized aluminum cages. The cost about $5 or so online, maybe $6-$7 at REI and other places. Brand name doesn't matter, they're all the same. They're lightweight enough you'll never notice the difference.

Put the money you save toward an insulated water bottle, Polar or Camelbak. Fill 'em about a third full the night before, freeze 'em, then fill with water before riding. They'll stay tolerably cool for quite awhile. Or use ice cubes.

Big difference between insulated and non-insulated bottles for cold retention. My non-insulated bottles begin with cold water but it quickly becomes tepid and then hot during Texas summers. If I haven't drunk all the water within the first 30-60 minutes that bottle gets shifted to the seat tube cage for squirting on my head and torso later in the ride. It's just too hot to drink later.

The tension can be adjusted to suit just about any bottle, including disposable bottles of water or whatever cold drink you buy at the convenience store. The aluminum will withstand minor tension changes -- we're not talking about extreme bending back and forth.

I use three different brands of aluminum cages on my hybrids. They're all the same. Never lost a bottle using 'em no matter how rough the roads.

My road bike has lightweight plastic cages. Cute but I doubt I'd notice any weight savings. And the tension isn't adjustable so I'm either yanking to free a bottle from one or worried about the other cage losing a bottle on a bump.