If you compare with the current "market" for signature campaigns, you'll see that many offer less than that, fixed, per week: https://bitcointalk.org/index.php?topic=615953.0
Then, as said, "low" depends (too) much on the user's home country.

But I do agree, however: it is "damn low" if you take into account that you'll ruin a not-bad-at-all account's future for 100$/week in a campaign that surely won't be here for ever (i.e. long enough).
And I'll come back to my original "hunch": it also depends on how much these accounts costed, since I am not convinced that it's the original owners who apply there.