If you are only racing once, Racesuit Rentals is the cheap and easy solution.
I high recommend SFI A5 gear over A1. By the time you buy the underwear you are not saving much money.
If you are going to race a while, you are likely to upgrade or replace a lot of your initial gear. I started with a treated cotton 3.2A/5 suit which was VERY hot in summer races and later upgraded to a Nomex suit which is much more comfortable. Now we race more in the winter and I occasionally wear long underwear too.
A LOT of friends and other races pick up high end second have suits from Race Image.
If you are diligent and resourceful shopper you can find good gear and very low prices. I bought a lot of my gear right after the 4th of July back in 2008. I got an SA05 helmet for like $65 and my SFI 3.2A/5 suite for hundred some odd dollars.
Way back in the beginning (2008), we were trying to find the best deals we could to keep our tab down. Now we spend more money on better or more functional gear. For example, we run FIA Enduro belts in the car now that are about $300 compared to the $65 SFI Latch Links we used in race #1.
Gear sizing is hard, if you can find a place to go try stuff on, I highly recommend it. My first suit was a little tight same with another friends. Another teammate recently bought a suit for his son which was the right size by the chart was way to big for him.
Troy
#35 LRE
1973 Datsun 240Z