I get lots of emails asking "how much", some from parked domains and others where I have approached potential end users.
Always be polite to people, however abrupt or rude they may be to you. They may have had a bad day or that may simply be their style. Politeness always wins although you might not get a sale every time.
Decide how much you need to sell the name and what you want for it.
I know very little about selling high priced names but I do know a bit about turning reg fee into several hundred dollars. IMHO dont try to squeeze the last cent out of every buyer - there is limitless supply of good quality low priced names out there that you can turn for a profit if you know where to look and there are tons of potential end users who are willing to buy, even in this recession, if you simply let them know the name is available and keep it to a reasonable price.
I simply name a price that I am comfortable with, taking into account the cost of Paypal fees, etc and ask them to make me a serious offer. The offer is often not what I am originally asking for but if they are serious we can agree a deal somewhere in the middle.
Then move on to the next name. Dont get attached to particular names at the low end of value - if you are making a reasonable ROI, take the offer and move on. Remember also how much interest you would get if that money was in a savings account and compare that to the return you can make on the name - no comparison.