Go to
www.saferacer.com they have a huge selection.
The theory behing a race suit is that the more layers the better as 3 layers will protect you more than 1 in case of fire.
Having said that the top of the line Sparco (3 layer) suit has a SFI 3.2a/5 rating (10 seconds exposure before a 2nd degree burn occurs) and it costs $1,500.
A $300 (1 layer) suit has a SFI 3.2a/1 rating (3 seconds exposure).
The 3 layer suit will be heavier and hotter. Plus you need to wear a t-shirt and socks etc.
So I would invest in Nomex long sleeve shirt, pants, socks and balaclava.
When you look at it you can easily spend $2,300 on safety clothing.
You want to be able to try the suit on as it needs to be confortable. That's why I like saferacer as they provide free shipping and if the suit is not confortable you just send it back.
I started with a cheap suit (SFI 3.2a/1) for the first track days, then added the Nomex under wear and I am about to upgrade my suit to a 3.2a/5 one.
I personally like Sparco, but Simpson, Alpine and OMP have good reputation.
Good luck.. it is a smart move... you do not want to skimp on safety.