The ONLY thing I've ever had truly work is the berghia nudibranchs. Tried tons of other methods to...well, not just no avail, but actually making things worse.
I accidentally introduced more aiptasia recently, and am waiting very impatiently (as they take over and slowly kill my corals) to be able to afford the good old nudis again.
Best place I've found to order them seems to be saltyunderground.com, or, if you can get there, I saw a vendor at reefapalooza CA who was breeding them and selling at a reasonable price.
As for removing them and sending them on to another person, that's fairly easy. Just wait till they come out at night and snag them gently off the glass. There's a good deal of demand for them, so your LFS might be interested in a trade...