On Baseline Research Blog is an article entitled “DIY Doing You In” (thanks to @Shanipedia for tipping me off to it). The author, Jeremy Juuso, states:
to have a decent shot at breaking $1 million in lifetime box office, your Q2 specialty film needs to open at better than $15,000 per weekend venue. The bad news is, if you’re engaging in a self-release or service deal, this will be a very tall order, as only 5 such films in all of 2009 managed to open so.