I might be buying some traffic, but need to know if it is safe to get the users to go to a page without adsense on it, with a link to my homepage. Is that OK, or will that get me banned?
If you mean just a link, it should be ok, but if it will look like a doorway, there might be a problem. If you think about buying cheap traffic, and this traffic will click link and finally will come to website with AdSense - it's not a good way. Most of bought traffic is from pop unders, the'll close website with link to AdSense site, and nobody will get there.
The problem is not adsense knowing it, it´s adsense knowing that your visitors increased like crazy from one day to another... and this is clearly bought traffic.
Buying traffic won't do anything good. You're not going to earn much and you will expose your AdSense account at risk. My advice is to avoid paid traffic and concentrate on organic traffic which converts way better.
the problem is those traffic will never visit your site. normallly those paid traffic will not be a real people. they will just go to specific page/site and never go throug to any links in it. Even if they do transfer, if the traffic to your site and clicks/ earning all are increase dramatically, it may raise a flag to google as well. so be careful.