We understand your concern. Unfortunately, right now, you need one of those components to capture more data than just email and name (which are stored by Joomla automatically).
For version 3.1 (due later this month), we're breaking out the profile integration to be plugin based. This will allow us to more easily add integration with other community components, or even allow some crazy people to roll their own if they want. One of the first plugins we'll be adding is for Usermeta, which is a simple way to add extra fields for the user without having to add all the weight that goes with a full 'community' solution. This may not be exactly with the 3.1 release, but will be shortly after.
Usermeta:
joomlacode.org/gf/project/usermeta/
Also, with Joomla 1.6, the ability to add custom fields for the user is built in, so we'll definitely support that shortly after it's released.
So, bottom line, I would recommend waiting about a month (hopefully sooner) if you must have fields. Alternatively, you can purchase now, get set up, and when 3.1 is released, you'll be able to move smoothly into a full profile import mode. Right now, if you absolutely had to 'do it yourself', we could definitely give you pointers on where to add what to do it yourself. However, that may add more complexity when 3.1 is released, so I wouldn't suggest it.
Hope this all helps, and let us know if you have pending deadlines. We can help you determine the best course!
Thanks!