Hi
I, like many others, are not on the hunt, to "find" end-users.
some domainers prefer to wait for offers or wait to get sales at listed BIN pricing.
still, those you mentioned prolly serve the purpose, for folks who send solicitations.
I hate to give advice to spammers, cuz I hate to get spam in my inbox and trust me, i get some every day.
but if you have to, i advise to be selective and exercise restraint when you start to "reach', for lack of qualified potentials.
imo....