I had a serious offer on a domain of mine - HookerAcademy<dot>com - a buyer offered $1,000 for it after I had registered it (about 1 month). At the time I should have taken the offer, but I was pretty much a newbie back then.
However, I buy domains that Expired daily, and sell those frequently. Including Beyondo<dot>com - which was sold for 1k after having owned it for about 1 month.
These names I put no effort into selling. But, both of which were a stroke of good fortune. I happened to like both domains and apparently, so did someone else.
Several members, including Chapel have done likewise. He registered PayForLinks.com (i think) and sold it no long after for $500 if I recall correctly.
Justin