Downloading from Bell has 2 costs to it. The cost for the ring tone, $2.00 or whatever it may be, and the cost for time spent on the mobile browser. Now, a lot of plans include some sort of "free" mobile browser, be it a certain amount of kilobytes free, or unlimited. Check to see what you have on your account and you'll know.
As for getting ring tones on your phone without going through Bell, you can download software widely available online, such as BitPim, and you can upload ring tones to your phone that way, with the data cable you purchased. Just google search BitPim and it'll come up with the info you're looking for.