Inexpensive Helmet?

It sounds like this will be your first race, so buying something triathlon specific isn't likely your best bet. basically you want to be safe and comfortable. Most urban areas have a Performance Bike chain, and that's going to be your best bet in your price range. Helmets are like shoes, they all fit differently and one isn't for everyone. Look for road cycling specific helmets, this will get you in the right area of the store. Try a bunch and lean towards the one that is well ventilated, has easy adjustments and is lightweight (you'll know when you pick them up what that means). The visor is personal preference. Most are removable so you can use for various sports. Color/style of the helmet are all up to you. Don't overthink it. Just my two cents.

Are you open to buying used? I have A Rudy Wingspan I would sell at that price.

Potentially. What size?

The Wingspan is a unisize (54-59)

If you don't want a used helmet check out Left Lane, they usually have good deals. Also Amazon, just got an LG Aero helmet for $55 bux (new). Good luck at the race.

Which much respect to the OP, but is your brain box not that important to you? A helmet seems like the wrong thing to skimp on, IMO.

Are you suggesting that only an expensive helmet will provide protection?

Are you suggesting the converse? Cheap helmet and safe helmet and not mutually exclusive and are not mutually inclusive, but the cheapest or "most inexpensive are not usually the safest. Considering its protecting you skull and brain, I would think that "inexpensive" should not be the number one criteria for selecting a brain bucket, IMO. I would think that safety and quality and comfort would be the number one priority. I do realized that helmets have a minimum safety standard, but still, I feel my point is valid.