From: Rincewind
I guess so. The biggest issue I see with these kinds of rares gaining price is don't some gold-farmers make hundreds of trial accounts for the spins so they can sell the winnings? Saw a thread about that here a while back.
Purple dragonstone present is members only.
Only way to get the hat is by trading by others, or getting all 5 presents and using them on each other.
Convert values for the other presents besides purple are low, trade value isnt much either.
So the trial accounts with daily spin thing has become less used after the summer was over.
And from a picture I saw a few days ago, getting a members item on the sof in a f2p/trial account, has a very low convert value (1 gp - 10k), or simply a discard item or subscriber to members choice. No convert, probably because jagex got aware of the farming.