You can beat Beast on Insane using nothing but Tickers. It is actually quite simple. Just keep bombing and calling out if someone is down so another Ticker can finish. Do not hesitate when trying to destroy barriers. Just go.
We did last night with two people who have never played Beast before, a guy who spent all of his money, and myself and one other guy who knew what to do. We made it to Wave 12 but didn't have enough money to get anything good
because the Guards were all bunched up together and would just insta revive each other. It's not hard at all.