AC will do you 0 good and depending on the car, could cost you the race (our Dustbuster minivan). Having just run NCM, you CAN run a first time team/car without additional cooling because you are going to be smart and run short stints so everyone gets to drive before you break.
Now long term, a cool shirt set-up if you are normal or a cool seat setup is you are weird like us is a very good idea. The former is more effective but more expensive and complicated while the latter is just as effective but by its nature will use more ice to do so.
Search this forum for newbie suggestions as it is extensively covered. That said:
Cars are easy, people are hard...paying, reliable useful team members are impossible to find
"How not to fail Tech" print one copy for each team member and your cage builder.
It takes about $4000-6000 to get to your first race
Do not sweat the budget, sweat passing tech...take the laps if you get them because you cannot win your first race.