I wouldn't assume the growth in binary size is anything like linear with code size (i.e. there's probably a lot of fixed overhead). And they appear to be using the "--dev" compiler profile, which is unoptimized and meant for debugging.
No, it isn't. That's about 6x the price in the US and at least 5x the price in Australia. No combination of VAT and shipping fees can account for that big of a discrepancy. You're probably just looking at a retailer that has inflated the price while they're out of stock. Try getting a quote from someone who has stock in your country ready to ship.
Being said that score in Page Speed Insights is pretty good (95).
Will be interesting how size increases with bigger/complex apps.