My basic rule is if I find a nice bike to add to the "fleet", I then retire (sell) one of the existing bikes. And the bikes have to be self funding (one pays for the next). This has allowed me to trade up substantially, without ballooning the keeper list. So I traded out my U08 for my Lotus Classique, my Trek 800 for a Trek 950, and my best "trade up" was my Schwinn Tempo for a Colnago Master Lite. By acquiring at the right price like you did, you can make some nice upgrades without spending any money.

The tough part is when you get one that is "almost" as nice, like the Nishiki Prestige I picked up recently.