A post getting 1000 upvotes earns $4. That's already quite a lot of upvotes, enough to get on the first page of a reasonably big sub. Posts on r/all (today, which may be abnormal) are at 10-50k, so would earn $40-$200.
$200 would be nice to have! But these don't seem like prizes that would motivate residents of first-world countries, considering that you have to have one of the most-upvoted posts on the whole site to win them.