I currently run a cool shirt (ice water/tubes/etc). I have tried a phase change cooling vest similar to your link and found it to be minimally helpful. I used to run a helmet blower with ambient air (no cooler), and also found that to be minimally helpful. The ice water cool shirt is an order of magnitude better than either of the others. Some race weekends it literally makes the difference whether I can/will go on track or not.

You can save some money by building your own cooler if you're reasonably handy and have the time. There should be at least one build thread on this forum, and several others on the interweb. That might also give you more options for fitting it in your car.