The cost for dial-up is $.75 (the cost of a local call if you dial up a local number); if you cannot call locally, it'll be the charge for a long-distance call and it can get pricey. Do not expect high speed as it will be over a regular phone line which can only be up to 56kbps. They will charge you per connection. I had trouble connecting at first and they wanted to charge me for all my failed connections, but I disputed those charges and they removed them (you could see that I tried calling the same number within one minute on the bill, so it's hard for them to justify....).
So, if you have a local number to call from your internet provider, you'll pay $.75 everytime you connect.