Yep, Wine Country Motorsports is great for “better quality / higher end” helmets in that area.
You can probably use your Shoei as long as it meets the minimum Snell rating (not sure of the age of your helmet).
As for the helmet “debate”… Price isn’t everything when it comes to the relative safety of a helmet. Snell / SFI / FIA rating isn’t everything when it comes to the relative safety of a helmet either.
The Snell rating is simply a bare minimum test that has to be passed. Nobody knows by how much any helmet exceeds that rating.
Once you get past that hurdle, fit is the next most important. A helmet that will pop off your head when you go tumbling is useless. I’ve had a cheaper G-Force helmet that fit great when I bought it, but the foam padding inside was of such low quality that after 2 days in it, the foam had been compressed so much that the helmet wobbled around on my head. It went in the garbage.
After that, I’d say it’s a bit of a crap-shoot… a more expensive helmet might be safer (see my example above for what you can get with cheaper helmets), but it might not.
A more expensive helmet will generally be lighter (which I factor into safety, especially so for kids), it will probably have more “bells and whistles” (probably not much to do with safety), and it will probably be better assembled with better quality materials (which may or may not impact on safety – again, refer to my example of a cheap helmet above).
I’d guess about 80-90% of the more serious karters are wearing Arai or Bell which will fall in the $500-700+ price range (there are a few other higher-end brands out there too), depending on which one fits the shape of their heads. Yes, they’re a little pricier than some, but I think most of us would absolutely argue that we are getting great value for our money based on the fit and overall quality, and we wouldn’t buy anything less. Once you’ve gone with a better quality helmet, there is really no turning back.