Quirks years ago; I think we were playing it when I was at school in fact. One thing I saw, but never got at the time, were the expansion sets, which added heaps of new traits to the game, firstly increasing the number of options in terms of weird and wonderful plants and animals and, secondly, making it harder to learn what traits were good in which environments*. Of course, by the time I wanted the expansion sets they were out of print.
They have been available as PDFs for a while now, and I have considered printing off my own set onto thin card and adding them to the game. True they'd have different backs to the original cards, but I don't think that this will be a huge issue - the information will be available to all players that a trait is 'original' or 'new' but I don't think it's information that can be of great use given that you still don't know what the trait is.
However I found out today that the sets are available via Noble Knight Games. I'm not sure if they are originals or reprints, but I think I know what I want for my forthcoming birthday. Even allowing for postage I can pick then both up for about $50, which to me is fairly reasonable.
Of course, there are other things I want for my birthday - decisions, decisions ...
*This is one of the two weaknesses of Quirks - the fact that it is possible to learn the values of each trait in each climate, thus eliminating any risk in challenges. Possible, but not easy. The other weakness is the fiddly mechanic of covering up the climates in which each trait scores 3 or more points, although I have seen a solution to this involving A4 plastic binder clips which I may try, as this was Catherine's greatest issue with the game.