Purely to encourage the posting of incomplete figures. Some people might be wanting them for kitbashing, or repairs, or to practice modding skills on, etc. Damaged figures are often fairly rarely posted otherwise, as people don't think they're worth posting or may not want to be associated with selling, shall we say, "pre-loved"-quality items. A formal subforum might, to an extent, legitimise such sales.

I also suggest it at least partially because most internet searches for damaged or junker items tend to result in 98% being from America, and while they might have a $9 price on them, that comes with a $90 shipping fee. Having somewhere to source parts and so forth in Australia could reduce member costs when trying to acquire repair material, as well as reduce the number of toys which just get thrown away and the demand (and thus price) for fully complete toys when people can't find just the individual parts they want.

Might also bump traffic a little on the "Ratchet's Repair Bay & ID/transformation Help" forum, and let members flex their more esoteric identification skills, as people ask for individual parts or junkers to be identified.