Notable in the explanations of limiting new members PMing in this manner is the avoidance of addressing the DISTINCT advantage given to long time members over newer ones. The fact still remains that 'established' members have the ability to respond to sales offers over those members who have used thier 2 PM allotment
It seems that the 'rational' for disadvantaging newer members purchasing ability is couched in providing 'Spam Prevention' for ALL members.
A very simple solution to this 'problem' and creating a 'level playing field' for ALL is to either require or request those that wish to offer an item for sale (a much smaller population than those with under 1000 'points') to include an email contact address.
With the proliferation of free email address availability, it is a much more minor inconvenience to establish a temporary address. To require those that will gain from the sale to comply with a VOLUNTARY requirement as opposed to the existing MANDATORY disadvantage imposed on newer members. If this is published within the rules applicable to SALES LISTINGS and it explains that the voluntary listing of an email address will INCREASE the potential market of the seller (inclusion of newer members ability to buy) then the SELLER would be the one to decide if they wish to LIMIT that subclass of new users or to advantage the long time members and forum administrators (who can be perceived as creating the advantage for themselves).
In short, the PM restriction can still remain in force and sellers can be notified that If they want to sell here they can deal with spam as a cost of the sale. OR they can can explicitly exclude a group of new members. it's up to THEM .. provide an email address (even a temporary one) or just rely on the PM system and loose some potential buyers. This way the 'establishment' somewhat levels the playing field for new member participation and leaves it up to the seller to define their own market penetration.