Tough call. It's hard to be objective here. Batteries are persnickety devices. It's not just about the flight count, but how they were cared for. You can turn a LiPo into a piece of crap after only 20 flights if it's not properly maintained and/or used incorrectly and/or stored incorrectly. Without knowing these variables along with the charge count - and seeing the voltage histogram across all 6 cells - it's hard to put a value on your battery.
IMHO, $150 would be a fair price (not a good price, but a fair price) for a well-cared-for, well-maintained, properly-used TB48 with 30 charges on it. Change any of those variables and the value goes down pretty quickly.
In lieu of actual data (screen shot of the battery's values in the Go App), we would have to know the battery's history.
Maybe somebody else could chime in, but that's kind of my take on the whole battery purchase deal.