On Orphan Black, did Alison and Donnie have any reason to become dealers in black-market prescription drugs? Were they just being rebellious? Currying favor the make Alison popular (and electable) in Bailey Downs?
From watching the show I would say it was primarily a way to raise money for Alison's campaign.
In Season 3, Episode 2, Transitory Sacrifices of Crisis we see the following:
"Alison and Donnie are at a soccer tournament, and they see Marci doing a campaign interview. Alison is sure she can beat Marci, but Donnie is worried about their finances, since he has no income. Ramon, Alison's drug supplier, comes over; Alison is surprised he's at a kids' sports tournament, but he says, half his clients are soccer moms, though he's working on getting out of the business to go to college. He congratulates Alison on staying clean. After he leaves, Alison tells Donnie they have a money-making opportunity. "
Later on this is reinforced when we see:
Ramon meets Alison and Donnie in the soccer field support building, and Alison offers to buy Ramon's entire business, inventory, client list, everything, he'll be clear and can go do whatever he wants. Ramon asks if they have the "stones" for this work, and Alison and Donnie say they do (Donnie a bit too enthusiastically). Alison comments, most of his clients are already in her circle.