There is very little value to these replicas. It is a layer an atom or two thick on aluminum. There is little extra value to these replicas and stamp collectors typically do not want them in their collections.
Apparently the GMI is a company logo and is not related to the kart stamp. There are other companies that put their logo as well for advertising purposes. The gold is the quality of the kart stamp (14k 10k 417 and so on) and is real because the company is accountable for it's stamp and it's logo.
If your trying to decide between Mario kart id buy Mario kart but Modnation racers is worth more than its price.
hai
Win a grand prix
Yes.
$25/$19
by getting all gold in a cc
It doesn't matter. Get all courses 1st and you can have a gold medal.
get gold in 150cc lighting cup
nope
get the gold cup in 50cc lighting cup.
Get gold medals in all 150cc cups.