Seriously, Berghias are probably the best solution. I don't know why some people haven't had success with them.
I had a huge(relative) aiptasia outbreak in my 16g cube and tried AiptasiaX, peppermints, boiling water etc etc with no success. All they did was multiply. I just kind of accepted the infestation and let them grow as they pleased. They were all over the display tank and in the rear sump compartment. I had always wanted to try Berghias but at about 15+ bucks piece and the cost of 1-day shipping, I could never bring myself to bite the bullet.
Luckily, I found a local breeder on craigslist that was selling them for 7 bucks a piece and willing to drop them off. I bought 5 of them for my 16gal, and in about a month they decimated the whole population of probably 150+ aiptasia from the DT and the sump compartment. The first night I added them to the tank I already saw them laying "spirals" of eggs. The tanks been aiptasia free for over a year now. Good luck!