I guess I am different from you guys.
I have bought and sold tons of cues, and how I have done it was buying some purely to flip and then some that I wanted to keep.
The ones I bought to keep, I have generally kept, unless I have a cue that I have wanted pretty darn bad.
I got my first Gus from Ken at High End Cues, and sold and traded to get the cash to get the cue. In that trade with Ken, I let go the best playing Southwest cue I have ever played with. It was Jason Miller's cue that I had refinished and it was incredible. It really doesn't bother me, as I would much rather have the Gus.
The second Gus cue that I picked up, I paid cash for it from a friend, and then sold about (4) of my "keeper" cues to pay for it. My friend wanted cash and the cues I sold, sold for more that what I could have traded.
So when I look back on cues I let go, I look at what I wanted a little more. I have been lucky in selling cues and making a little or trading and adding a little cash to get something a little better.
Ken