Continuing the "one lens" series
which lens have you always wanted to get, but you ended up never buying? For whatever reason - you have another lens that you are happy with in that focal length, or because it got too pricey or hard to find, or simply because you never got around to go looking for it?
I think for me it's the Samyang/Rokinon 16mm f2... I have always wanted it to complete an "all primes" kind of kit (my widest prime now being 24mm, which isn't really that wide on APS-C). After the DA 16-45 came by, and f4 ended up being enough at 16mm for most of my uses, I just never got around to saving up for one, even though they're not that expensive in the used market, though they seem to have become a bit hard to find. I still want one, but I have no idea when I'll finally get it... or if I'll ever get it.
I also wanted a 17-50 f/2.8 lens (or 16-50) but that doesn't count, I think, because I no longer feel the urge to buy one, also due to the DA 16-45.