Interesting question, I'll break it down by types/brand of firearm:
M1 Garands
I purchased (it was by lottery, and limited to one per lifetime back then) a DCM M1 back in 1982 (IHC rebuilt in 1962, pristine condition). That satisfied me until 2000 when I found out that I could buy more from DCM (CMP). Anyway, by 2006 I ended up with about 15, mostly nice shooter grade rifles. I then cherry picked the two really sweet rifles from the collection (SA 5.7 million s/n, CMP Collector Grade in 99% condition and SA 5.9 million s/n correct rifle in 97% condition) and sold the rest over 3 1/2 years.
Swiss K31 rifles
From 2003 through 2006, I acquired seven nice ones. I again cherry picked the three best (1950 shooter in 85-90% condition, 1952 in 90-95% condition and 1957 in strong 95% conditioin) and sold the rest over the next couple of years.
Makarov pistols
From 2000 through 2007, I acquired six nice ones. All six were were relatively inexpensive except the Russian PM, so I've kept all but one. I got rid of one I had in .380 cal. The core collection consisting of the Russian PM (1976), East German (1962) and Bulgarian (1981). The other two are are Russian commerical models made in the mid 1990s.
S&W 2nd and 3rd generation pistols
Since the mid 1990s had owned three 3rd generation pistols, but they had ended up with my brother and a close friend. Then, in December 2006, I got serious about 3rd Gens. From January 2007 through late 2009, I aquired approximately 25-26 pistols. All but two of them were 3rd Gens and all but 3 were 98%+ condition. Between late 2009 through 2011, I culled my collection down to 18 3rd Gens and one 2nd Gen. I like my collection the way it is currently and I'm not actively seeking more. However, if a pristine 3rd Gen with a
really great price were to present itself (especially a 1026, 5904 or 3914), then I might have to jump once again.
S&W revolvers
Geez, I've purchased and sold a lot of these since the mid 1970s. No particular focus, but I am pretty proud of my 629-2 w/5" bbl., 29-4 w/3" bbl. and 681-3 CRPD in .38 spl. w/4" bbl. All three are in 98%+ condition.