Actually, the cheapest and most versatile rig you should look at for your purposes is a pocket dolly. ZaZaCast Films has written a pretty detailed posting on just how to make your own pocket dolly for right around $170.
Not only does the pocket dolly work wonders for lateral movement with cameras like the 7D, but take a look at what you can do in this video at around 01:10 with a second fluid head :
I have this rig...and love it!!! http://www.kesslercrane.com/index.php?option=com_content&task=blogcategory&id=41&Itemid=104 Super easy to set up...super portable, and really easy to operate as well. I can't say enough good things about this rig...and if you have a good sturdy full sized tripod, the jib arm itself is only 350, which is dirt cheap. For a lightweight hdslr most jibs are OVERKILL and this one is JUST RIGHT!!! Woohooo!!!