Hi,
i don't do outspam
but, either way, you have to know how much you want for the domain.
the initial problem i see is doubt,
in that you are already scared of a potential walking away, because of price.
the next issue,
is knowledge of the domain you are selling.
as in, how long have you owned it, any previous offers, how many visitors does it get, does it earn any ppc revenue and if so, what do those metrics look like.
if you just registered it or caught from backorder, then what do you really know about the name?
once you get to know your domain,
then you have better idea of it's "as is value", along with any potential value, for those you are spamming.
this way, at least you won't have to lie or mislead, by making untrue statements relating to possible usages and potential value, to that prospective.
such information at your disposal, gives confidence not only to you, but can be conveyed to potential backed by hard data, if needed.
on other side of that kiz-zoin, when you get inbound offers, inquiries,
then leverage is on your side... since you already know they are interested in your domain.
at that point, you can exercise the make offer option or give a price.
imo...