Are services allowed to be sold here?
Why, not?
The announcement is posted in the 'for sale' forum category from a due's paying APUG 'subscriber.'
Also, the post is definitely 'analog-photo' related (for the hybrid workflow process).

It's really no different than somebody offering to repair a shutter, change capacitors in a faulty flash,
drill a lens board, or fold a new set of bellows for a fellow APUG member.