$300 = 420 Steem
420 Steem = 0.02 STU upvote for 100% (0.01 after 90% :))
meaning, daily 0.2 STU, weekly 1.4 STU of upvotes without 25% curation and 50% of SP -.-
if my math is not failing me. I hope it does but..

for 1 STU upvote you need 28.000,00 SP

these could be usable on specific dapps but not in the main sites.
Say steemhunt (clone of producthunt) could benefit from this approach, has a targeted audience, has a front-page so why not.

where will that fashion ad will be displayed? near my logo design post? :(