I used to use TA a lot and made well over $250 selling twitter package gigs on Fiverr until Twitter realized what I was doing and banned all my accounts.
Some quick points:
1. I never saw much success in using the wait and reply method.
2. No need to buy the AC. It is a waste of money and time. I used to buy accounts from a site and on Fiverr, but I'm not sure if he still is on there or what that site was. (I haven't used TA in a long time).
3. When I was using TA I had over 2000 accounts and for a solid 2-3 months I was golden. I didn't use one proxy. But that could also have been my downfall as someone said previously - twitter is getting better and better at catching us.
I think the cost/benefit of TA in bringing traffic to a site is pretty bad. You really need to be thinking of how to sell twitter fans or build accounts to sell or something to SELL. Therefore, before you buy TA, come up with a plan of how you can make money SELLING a service.