I thought my first "really good" domains were ones I picked up for US$50 form the Great Domains special offers (NSI's unpaid domains I think).
At the time I thought that 4 letter domains were the best thing out, and after spending hours and days browsing through the 1000s of names, I invested the little money I had in:
dego.com
sloc.com (not realising it was the olympic acronym)
elvy.com
keth.com
tuel.com
rork.com
I now realise that there is a lot more to life than four letter domain names
I picked up most of my other decent names early on from deleteddomains.com for $9. But once again, this took a lot of time.
Pretty much all of my best sales have been for names that I didn't consider to be "really good"!