Hi,
I have the Jet 10-20 sander which I got rather then a larger size because I don't have shop space for one of the larger models. You can read about it here:
http://www.rockler.com/product.cfm?page=17140
It really works quite well for me and I'm glad to have it, if I would have had the room I would perhaps have gone for a larger size unit.
This type of sander works well for taking off bandsaw marks, even cleaning up after running though a planner, and works for odd grains that don't plane well. It will do thickness sanding but this model would be under powered for major stock removal... you would need to make many passes. One of the great things about these machines is the roller pressure is much less then a planner so it does a better job of making things flat.
As far as homemade projects I have two of them I've posted here. One uses a shopsmith 6" sanding drum and a small bit of woodworking to provide a version of an sander that works like the sand flee. It is dirt cheap to build and uses parts you might already own and scrap pieces of plywood. Thus the title "sand almost free" you can read about it here:
https://forum.shopsmith.com/viewtopic.php?t=863
The next project was something I called the "sand-ed" and is larger being about sand flee size. A lot of details on the construction can be found at:
https://forum.shopsmith.com/viewtopic.php?t=5342
These last two projects are a lot different then the drum sander I own, they have a different function in life and should not be confused. The sand flee type sanders are just cutting with the grains of sandpaper and are not made to remove large amounts of material. You may thing of them as being more like hand sanding but with even less pressure.
Ed