Sgt_Kickaxe - 8:25 pm on Oct 26, 2010 (gmt 0)
Two schools of thought.
#1 - Sell when you are offered what the site is worth to YOU. Reasoning: If it's a good deal that makes sense do it and don't think twice.
#2 - Never sell your income unless it's to buy an increase in income. Reasoning: unless you have a plan in place that will pay you more over the long run, including covering the period of time in which you don't earn, it makes no sense to sell.
My advice is the same as any stock investor would give you. Know your risk level tolerance and stick to it. Unless you predict a drastic reduction in earnings in the near future, or have a killer new business plan ready to go, it makes financial sense to keep earning on a monthly basis.
At 65 sell and go enjoy life, you've earned it. At 20 ride it out, you can still afford to rebuild if all is lost and the upside is greater when you own sites than when you don't.