4th Grade and Up
For first vehicle, we usually recommend Arrma or Traxxas as a brand. For more "race" or advanced vehicles, Losi and Associated are good brands. There are many other great mainstream brands, they might just require parts ordering online or at specific hobby shops. Such brands like Kyosho, Techno, Hobao, Yokomo, Kyosho, Tamiya, X-ray, etc.
We race 1/10 sized vehicles generally. You can get smaller (1/14, 1/18) but it will get pushed around a bit by the larger vehicles. We definitely recommend the 1/10 over the smaller ones.
Buggies are usually nimble and light. A Traxxas Bandit or Armma Typhoon would generally be a good vehicle
Trucks are similar to buggies, but a little wider, a little more forgiving, but a little heavier. Traxxas Rustler or Armma Granite or Vorteks Boost
Short Course Trucks tend to be more rough and tumble, for those it would be a Traxxas Slash or Arrma Senton Boost
Traxxas has a number of options for each, ranging from their basic ones (good for beginner) which are the "XL-5 Brushed" models to the faster/more advanced VXL brushless.
Arrma offers different options, but we would recommend the "boost" models as they are basic, but have upgrades to make them more advanced (such as going 2wd to 4wd) later on as one gets more experienced.
Both come "ready to run" or "ready to race" which means they come assembled and pretty much ready to go. Most of the "intro" models come with a 6-7 cell NIMH battery which is fine for racing in the club.
There is another battery type, LIPO, which comes with some of the more advanced models, but that has specific requirements. If the one you end up looking at to get has a LIPO, you can reference the battery article to understand what is required.
If the above ends up being more than you wanted to spend, Amazon has some off brand cars (1/10 scale) that may be ok to start with. We would recommend ensuring the vehicle has replacement parts available.
Prep Members
If you're interested in a race ready vehicle, that can be used when graduating to a full member, please reference the 4th grade and up section.
Otherwise, any vehicle is allowed, and since the category is not allowed to be competitive (no individual trophies), whatever is fun to drive. The key is to enjoy the racing, so if you find the vehicle isn't fast enough or too "kiddy", then it may be time for an upgrade.
For this, if you want just a temporary vehicle that would only work well in Prep, you can get something off Amazon for around $75-$100. They would be considered somewhat "light" race grade and likely a smaller scale (1/16 or 1/18 vs 1/10), but would be faster then your average radio control car from Walmart/Target.