It all depends on how aggressive the site is on cracking down and banning dummy accounts and the cost of the "upvote packages" (which I can't seem to find). On

It all depends on how aggressive the site is on cracking down and banning dummy accounts and the cost of the "upvote packages" (which I can't seem to find). On Metafilter they seem quite aggressive so the accounts have very limited value/lifespans. A dummy account on reddit may be allowed to vote hundreds of times before being banned so the price per vote becomes minimal.