I am looking to buy an oscilloscope that will last me a few years. Application is everything but RF: digital and analog with as wide a frequency range as possible/affordable. I would like to buy used, but I would prefer Craigslist in the NYC area to Ebay, so I can check it out before I pay money. Yes, I know Ebay has escrow and if the pickings are too slim on Craigslist I'll go that route. I need something that will allow me to do repair and testing on mixed (A/D) systems in the medium-to-near term. My questions are:
What is a good entry level-price range? Barring any definite statement, how much will I spend per, say, 500Hz additional frequency range?
What features should I look for? Again, what is the price point on each feature?
What is a reasonable minimum I should expect to spend?
If buying used, what tests should I perform before paying?