I too have started out haphazardly. The first one was one that I saw and liked (659) and the price was good. The second was cool looking (459) as the owner had had it re-done in all black melonite. The third was because I like .40 cals (4046). The most recent was because I wanted a first gen with a box for investment purposes (39).

Now I am building up funds for my wish list (in no order):
59 (two-tone)
539
439 (nickel)
745 (two-tone)
45xx
10xx
4013tsw
5906
and another 39 to shoot

And I'm sure I'll see others and be tempted.

It's an addiction!