For what it is worth @ZiderEyed and @Ska Junkie, there is already a 4% levy on all transfers paid by the purchasing club which is used by the PFA. This would've been used to foot the shortfall in wages during the difficult periods faced by Bolton and Bury. It doesn't go the extra step that you stated previously, in terms of being used as a more concrete fund to keep the club afloat but it is a good idea. In reality, if they completed annual proof of funding checks for owners, it would alleviate many of the issues early doors.
It's a sad day for Bury football club day and really hope they survive.