I've collected diecasts for nearly 15 years, mostly in 1/43, although I have some bigger stuff up to 1/16- the main theme is rallycars, mostly 1950s/60s through to 80's Group B- (although there are quite a few outside that theme-60/70's touring cars etc), but I also collect Minis and Group C sportscars. Total must be 5-600 by now, plus a small collection of kits that fit in with the rest of the collection- Tamiya 1/24 Group C, old rally cars, that kind of thing. I've also dabbled in restoring/repainting old diecasts to make things (particularly early 60's rallycars) that aren't available otherwise
Some of the nicest things I've got are a couple of 1/43 white metal handbuilt 60's rallycars I bought a few years back which were painfully expensive, but couldn't resist them at the time-
http://www.whitemetal-model-reviews.co.uk/CR02.htm