If I were you...and owned this name, I would not sell for less than 500k...and may not consider anything less than 7 figures. If It were me...and I owned this name I would consider selling at 150-250k (of course if the ROI made sense).
The reason I say this is that you seem to know a thing or two about forums and may have an amazing business plan for this name which will make you mid 6 figures + each year. If that is the case and you don't need to raise cash right away...why settle for less than 7 figures?
I found myself turning down a 300k offer late last year for this very reason...on a great domain name I know a thing or two about in the category it defines....and am developing into a real site, with a real business plan behind it (and sinking real money in it)....there are many people who would have sold for half the offer I got, but I believe I know how to maximize the potential (and I hope I am right).
Hope this helps. Good luck with the negotiation.