I seem to remember last year at some point the rare item store got a new batch of items added and those that are now limited rares were discounted heavily. Question is...does anyone know when that time is this year? or is that something Jagex hasn't mentioned?
Rare item tokens don't just come from TH. You can get them from different events, most noticeably Vic the Trader.
Like Vic the Trader and other events that give rare item tokens (e.g. Smashing Relics, I think) they don't come on a fixed date.
When they come, they come... but the best think to do is just hold onto every rare item token you get because I think it is likely new stuff will be added and old items will get discounted based on past experience.