Aweber is cheap and you can make ALOT of cash if you learn how to use it right. I would read up some tutorials and learn about email marketing and make sure you can try to use it efficiently.
why dont you use this -http://www.mailchimp.com/ - it guarantees no spam entering and its free of charge until 500 mails monthly
Aweber will not let you import your leads (maybe a few at a time) and the leads will have to opt in again. Groupmail is good
Even my wife can use Mail chimp well and she hates techy stuff. It's a monthly payment but does allow small mailing for cheaper rates. A thought for you, if this group are really going to be worth mailing, then a small investment in a decent system might well be wise? If they're not worht that small investment then maybe they're not worth mailing? Turnover is vanity, profits are sanity B.
You can do some interesting stuff with Mail Chimp that you can't do with Aweber. However if you have basic needs, Aweber will serve you fine. Tyrus
Aweber gets hacked. Loses emails. Not the first time. http://www.bustspammers.com/aweber-hacked-email-addresses-stolen.html