Yes, pretty much anything can be delivered to Australia. We've sold quite a few custom
badges to customers over there.
Your gut is correct IMHO. When people ask my opinion on whether to go with matte or glossy, the answer is always glossy for the specific reason you mentioned--the lower/central parts of the rear bumper is glossy so go with the option that's consistent.
Customization is not cheap. Doing things the RIGHT WAY is not cheap. However $85 is not expensive either--especially when we're talking about a $40-$50k car. You're probably stuck on KDM pricing as the baseline. Go check your local dealership to see how much the North American-spec Stinger lettering costs. That's much more realistic.
Also, the Stinger store "carbon" is hydrodipped, which is hardly a showroom finish. Hydrodip doesn't have professional clearcoat either. As a middle ground comparison it actually makes sense though--basic, middle ground option, best option. (I'm not even going to bother addressing the spraypaint thing). Obviously the cost will increase as you go up in appearance/presentation. I can assure you there's no "ridiculous charge" at all. If you think we're making a mint on these, you're fooling yourself. Keep in mind there's a reason why no other vendor is offering something like this. It's just not easy to do.
The black ones on Ebay are 3D printed. There's a reason why the seller doesn't give real close, accurate pictures of what it looks like in person.
They're usually in stock. The time estimate is there to cover our asses. It's not like we can stock tons of these at any particular time-10-15 or so us what's usually done in batches. These can either sell out in a week or sit on the shelf for 2 months. The Kia market is miniscule and can't support much inventory investment.