To expand somewhat on what Jake posted (and add my own spin), the limited access to the classifieds is an intentional design, not an accidental oversight. Very few people are in this hobby to make money and most are very selective about the people they are willing to sell their pieces to. Recasting is a major problem, however so are people claiming credit for work that isn't theirs and new members who seem excited at first, purchase a few pieces, lose interest, and then liquidate everything on Ebay.
It also cuts down on wasted time - this tends to be a very "young" forum and quite frankly, some new members simply may not have the financial resources to purchase most of the items that are listed. This is not an inexpensive hobby and hopefully by the time a member has spent enough time to allow access to the classifieds, they have a better understanding of what some of these pieces go for.
Many artists go so far as to request that buyers notify them before they re-sell an item, simply so they can keep track of where they end up. This is a courtesy that when extended, is much appreciated. By restricting the classified to established members, it helps (at least a bit) screen out those that are either looking for product to recast or who really aren't serious about this hobby. Your posting history provides a record of how you interact with people and to some extent, your personality that sellers can research before offering something.
Personally, I don't care how much money you offer, if I don't know you or at least have a comfort level with you, I won't sell you one of my pieces.
Lastly - it's a "privilege", not a "right" and thus needs to be earned. If you are serious about this hobby and the 405th, then your activity level should be a non-issue anyway.
Everyone gets an opinion and that's mine...