ATTENTION DIY Cool Shirt guys introducing Ultra Chiller

FWIW, the Engel Cooler/DryBox is the same cooler that the FAST Systems cool shirt system uses for their cooler:

http://www.engel-usa.com/coolerdryboxes.html

It's kinda spendy but it does have a very positive latch preventing the contents from spilling during cornering. We just use large Coleman coolers in our DIY versions and strap them down in the car with a ratchet strap and then they don't leak either.

If its a decent machine it should be able to stitch over the tubing without any jig or attachments.  My wife looked at the FAST shirt and said  "My machine can stitch like that".

No one should buy a cooler kit.  It's easy to make one, with all the correct fittings, that doesn't leak, that is as big or small as you'd like it (whether high capacity so you don't have to refill often or a specific cooler footprint to fit your car setup).  Anyone can follow the directions previously posted here and have a very high-functioning cooler kit (including external lines and insulation) for <$45.

The FAST/CoolShirt shirts, however, are pretty slick.   Their shirts, unlike the less expensive shirt listed a couple posts above and any shirt you're likely to build, use more cooling tubing, have two cooling circuits each front & back, have cooling lines above the chest and over the shoulders, are unlikely to kink in use and will wear just about like a normal t-shirt. 

I fabbed up two different designs of a cool shirt... also with the use of a 'fancy' sewing maching with 'fancy' stitching and the shirts were unwieldy to get into/out of, required a ton of adjusting once on the wearer and the tubing was prone to kinking - I tried 3 different kinds of tubing - different sizes, different wall thickness.  The shirts definitely would get you icy cold, but were such a pain the ass to use and/or would kink and a circuit(s) would stop flowing.

As many others who have gone the DIY route have learned... it's worth buying the shirt... it works very well in all regards and isn't that expensive; the cooler & plumbing is stupid simple to fab, will work as well if not better that the retail version and is considerably less expensive.

Despite poo-pooing a DIY shirt, I found it can work quite well if you're not in a racing seat and/or getting in/out of the shirt with any regularity.  As such, I'm using one of my DIY shirts with a DIY walkaround backpack cooler.  I'm taking the rig to Capitol Offense/Summit Point and Judge Phil - assuming the weather is compliant and the system holds up - will be wearing it all weekend.  Interestingly, the Honorable Judge Phil said he was only interested if it's totally hooptie-style.

Hooptie it will be my friends!

It would have to be very bare-bones to get under $45.  A bilge pump will run nearly $20, two dry-break quick-disconnects will run near $12, and 10 ft of 3/8" tubing will run at least $5.  That doesn't allow for fittings, clamps, the 3/4" tube to get out of the bilge pump, and so on.

I'm in the process of speccing out my own system for our team.  I'm looking at the following:
$18 Bilge pump (already purchased)
$32 Multi-function switch with continuous on as well as one minute on and one, two, or three minutes off (already purchased)
$13.34 quick disconnects for connecting system to shirts
$2.34 quick disconnects for draining the system and/or the shirts
$28.46 through-wall fittings (could be omitted in favor of just running pipe or tube straight through)
~$8 for other fittings (tube-MNPT to connect to the through-walls)

All fittings are online-priced via McMaster-Carr.

That doesn't count what I've already spent on silicone sealer and tube clamps (somewhere between $5 and $10), nor what I'll have to spend on 10 or 20 ft of 3/8" ID tube (probably $6 to $12 at Lowe's) as well as a small length of 3/4" ID tube to get from the pump to a step-down fitting.  It also doesn't count a cooler, which was bequeathed to me by a teammate for transforming into the cool-suit cooler.

For all of that, it's still a bit cheaper than the kit that was pointed-to above, and less than half the price of buying a 24 qt system retail .

Website is back up. Sorry for the downtime. You can always reach me by phone or email. BTW, I spent over a year and a half finding the right tubing for my shirts and vests. It stays flexible, provides more cooling, is more puncture resistant, and is field repairable. I believe my product is superior to the competition. Thanks, Chris

For those with an engineering bent there is some math in this post...

The shirt system will need to pull out pretty close to all of the heat generated by the driver at least during summer down south or you will have heat stroke issues fairly quickly.

At rest doing nothing a man consumes energy equal to about 100 watts.   Moderate effort, like dancing or racing fairly conservatively is closer to 250 watts and true exercise like sports or racing a manual steering ill handling beast is about 400 watts.   These are for your typical 185 pound male person, YMMV.

400 Watts for 1 hour will turn around 9 pounds of Ice into a bunch of warm water.  That's about the rate I use ice in the cool suit I run in the Dauphine but that car is all manual and fairly hard work to drive.

144 BTU to melt 1 LB ice, 144 BTU =~ 43 Watt Hours
400/43 = 9.3 pounds Ice melted

So with the heat gained from the car interior and me driving I need to dump about 400 watts continuously to stay cool.  Pretty close to what I see experimentally ( at 100 degrees air temp in Houston in July )