I've been looking for a Digital Oscilloscope! How long have you had this one for? Why have you decided to sell it?
I've only had it for a couple months.  I figured it would get a lot of use, but it's pretty much sat on a shelf.  It's only been used a couple times.  I'm looking for 490 for it.  I think that's fair as I'm including a 17 inch LCD monitor and two 150MHz probes.  Is this your first Oscilloscope or have you been using one for a while?
It's my first. I've used them in the past, but I've never owned one. They're a bit out of my budget! However, I'm very interested in this one. Would you accept an offer?
I have a little bit of wiggle room, but not too much unfortunately.  When I got this one I went pretty high end.  It has a 100 Mega Samples a sec and can export data to PCs.  It even has internal storage.  What do you think is fair?
I was hoping I could get it for $345. I can assure you it'll be put to good use!
Hmmm I can't go that low unfortunately.  You said this is your first one.  How about we go 440 and I can spend a couple hours showing you how to use it and can even throw in some replacement parts I have.  
I understand. How about $400? That's about all I can afford at this time. 
Do you have an old fishing pole or skis that you don't use any more?  I'm looking for one and would be willing to do 400 if you have something like that I could spend the season using.  
Yes! I can spare a fishing pole. So, $400 plus a fishing pole?
400 and a fishing pole sounds great!