Is that $500 or above Carnauba Wax any good?

Any Carnauba Wax or basically any final layer that you apply is merely a form of protective cosmetic.
It does not correct your paintwork's flaws.

As to whether a $500 and above Carnauba Wax is any good, it fully depends on the quality of your paintwork, and the extent+quality of surface prep work (aka compounding and polishing) that has been done on that paintwork.

On a brand new Mazda (example) imported from Japan, if only a mild polishing is done, and topped with super premium Carnauba Wax, you won't be impressed. On the contrary, on a new VW or BMW, you'll see a much more impressive result.

The lesson here is:  Your wax or final layer contributes the LEAST to the final results.
It's all in your surface-prep (eg: sanding, compounding, polishing etc)
It's 100% identical skincare.
Your surface prep is "skin treatment/skin correction". Once your skin is looking at its best, then its time to progress to using the best "cosmetics" (waxes, sealants etc) you can afford. Get your "skin" right first.

If the paintwork quality is average or above average, and extensive prep work has been done, you've already achieved close to 90% of the final looks, and any quality waxes or sealants will provide that last 10% in terms of richness, gloss and optical depth. No wax, no sealants and no coatings can serve as a "magical last layer" that'll turn an average quality paintwork (+ simple polishing) into a show car look that'll turn heads. 90% of the final looks will be determined the extent of the surface prep and how your surface prep were done.

Most synthetic waxes (eg Meguiars NXT) and natural carnauba waxes (eg Swissvax, Zymol etc) tends to darken the colour, which enhances the ILLUSION of vibrancy, depth and gloss. This is especially great on dark colours and black.

 However, IMO, on silver, white and other light colours, I don't want any waxes or LSPs that has a "darkening/richening" effect, as they tend to make these colours appear less bright and appear dull, without the bright "popping" effect. I never use Carnaubas on light coloured cars or pearl finishes. On such whites, silvers and light colours, you could try an average of 3 layers of a great synthetic sealant that doesn't change the colour at all (eg: Zaino Z2Pro, Jeff's Werkstatt, Klasse Twins, Duragloss 105, hundreds of Jap synthetic sealants, Turtle's ICE etc).

 Certain synthetic waxes such as Collinite 845 is also superb on whites, light colours....and especially silver. The above approach makes the silver and white look as "bright" as possible with no darkening effect. These colours will look vibrant and reflective, giving the car a sharp look.

Premium priced tyre shine - necessary?

I have tested more than 25 different tyre shine products over a 10yr period and my conclusion is: 1. The more expensive ones will usually remain on the tire sidewall longer than the cheapo ones. Note that I said REMAINED. The product might be chemically present on your tyre sidewall for 1month, but it does not mean your tyres will be super black with a wet look for 1 month with/without washing. The mere presence of the chemical on your sidewall has nothing to do with how fantastically glossy your sidewall looks like. 2. Any tyre shine product is affected by heat. It might look nice and glossy upon application, but drive at 60mph for 30mins, and you'll that the initial wet look has died down to a more "satin shine" finish. 3. Any tyre shine's gloss level is hugely affected by the sidewall's material (type, texture etc). Most ultra low profile tyres tend to exhibit a much higher gloss level when you use even a cheapie tyre shine. When you review tyre shine products, always test it on the same brand and same size of tyre for an accurate impression. 4. The best results are obtained on 100% clean sidewalls. Don't waste car shampoo on your sidewalls. Wear gloves and brush your sidewalls using powdered laundry detergent or Bon Ami (or other powdered detergents) or dishwashing liquid or full strength multi-purpose cleaner. Scrub until the suds are no longer dark grey/black. Dry the sidewalls completely, and apply your tyre dressing.

Expensive Car Shampoos - necessary?

Car shampoos are the highest volume sellers in the detailing products market, and naturally, mftrs have CREATED a need for premium-priced shampoos to entice car enthusiasts. Premium-priced shampoos with glitzy packaging and hyped with "marketing fluff" aren't gonna make your car any cleaner than a normal car shampoo. If you know how to wash your car properly,spend the proper time to do it correctly, and wash often, any ph-balanced car shampoo from any reputable mftr will the job equally well. If you want your layer of wax or sealant to last as long as possible, MINIMISE contact with any car shampoo or any detergent. Wash with your mitt and rinse immediately. There is no benefit in leaving the shampoo suds on a surface that you've already agitated with your wash mitt unless that surface is extremely stained and thus, require extra dwell-time to loosen the stains. If you do a blind test on 2 identical cars, with each being properly washed with different shampoos, no one can tell the difference. Can you tell which brand of shower gel I used last night? NO.