Hard to guess exactly without knowing the domain/company. I'm a passive, patient, end user only seller. I look at a domain and value it based on the right end user buying it. I usually have info on buyers name, email, ip, phone as I use my own sales pages but even when they come anonymous sedo, etc... I won't really have any regret if they don't buy as the domain has already been valued by me for an end user only sale and not so much on who the buyer is as I only sell to the right end user so I shoot my price. If they pass no biggie they weren't the right buyer.
So hard to tell someone else what to do as financial situations are different, maybe domainer A doesn't need the money where domainer B needs to feed 5 kids. I can blow a sale and not give it a second thought as I don't look at the buyer and go he's broke let me lower my price or he's rich let me triple it. My advice would be to formulate ballpark ranges on all of your domains so when offers approach your not so much looking at who the buyer is but sticking to your previous research of domain value based on domain quality, end user value, ROI potential, offer frequency, amount of possible end users etc...
I've got one now that I bought quite a while ago for $8 and I declined him at 10k as it's worth slightly more and it gets a few offers every month.
I've got another one right now that came in at 500 declined, then 1000 declined and now 9 months later as they won't go away were at 4000 but doubt I'll sell for less than 7500-10000 as once again worth more. This one tried to be sneaky and anonymous but I've connected all the pieces, on their second round of funding along with their site being in beta mode, just not sharing with them that I know who they are. Nothing more than a gonna have to pass but thanks for the offer.
So guess my point is who the end user is can swing pricing but just because someones rich doesn't mean they will pay 3x the value of the domain. And just because someones broke doesn't mean ya let a gem go for pennies. Also clues you'll pick up on, how fast do they respond=urgency, along with saving/analyzing all emails as sometimes ya can read between the lines or things that were said in email #1 change in email #3 without them realizing it along with googling everything names, phones, emails, company names etc...
So without knowing the domain/buyer hard to say where I would shoot but guessing it would definitely be 4-5 figure range. But your formulation should be domain quality research, end user research along with your current financial position. Always be nice so if ya do shoot for the sky above their heads possibility to recoup it at a lower figure. The take it or leave it usually doesn't go far in continued negotiations.