I'm rubbush at estimating prices. For example, I sold Forex24.com a few years ago for £250. It turns out it was the trading name of a Swiss bank. Goodness knows how much they would have paid, if I had done some research before quoting a price, I did dicuss the name here, and the general opinion was that it was not worth anything. I guess that in the end it depends how much it is worth to the buyer. That's a trite statement, and I don't know how you can discover his buying limit. It's probably a question of negotiation. I've had 3 different enquiries for OffgridRV.com, and they seemed to be from different locations in the US. They all stated that it was the name of their businesses. I asked for 0.2 Bitcoin from the last enquirer, and I didn't hear any more from him. GD values the name at $1,800+, so I didn't think I was that far out in my request.
Some years ago I received a phone call from a guy who just said "How much do you want for YachtBits.com". He caught me out, and my knee jerk response was £250. His instant reply was "Where do I send the cheque?" It turns out he owned the co.uk, and he was starting to sell internationally. All of those name were ones I picked up for reg fee, and I suspect my thinking was clouded by the low acquisition cost. I've now learnt that the price you paid has nothing to do with the potential sale price.