Not everyone can afford a full-sized scanner or all-in-one device. Nor does everyone need such a device. If you scan very infrequently, then it seems quite wasteful to buy a scanner. At this point in my life, I fall into that category. I'm scanning more and more over time, but I don't scan regularly enough to warrant a scanner. So, what to do?
Build your own scanner.
Before you say it, you don't need any mechanical ability to build your own scanner. Sure, mechanical ability helps, especially if you want your do-it-yourself scanner to look good. However, an ugly scanner works just as well as a pretty one. As you can see from my pictures, I have no mechanical ability whatsoever, and have built the world's ugliest scanner. That's ok, because it works fantastically well.
You can find step-by-step directions on creating this amazing simple device here. I can't take credit for the idea - I just followed the directions. The result is simple and brilliant. With the use of two coat hangers, a couple wire ties, and a rubber band, I created a homemade scanner. In the picture my iPhone is mounted to the stand - and it works ok, except for lack of a flash. If you have good lighting, it does the job just fine. I actually prefer to mount my digital camera, since it has a flash, which solves the lighting problem.
How does it work?
Mount your iPhone or digital camera using the rubber band. Place your document under the stand, and snap your picture. Rinse and repeat for any document / receipt you want to scan. Hook up your digital camera to your computer, and copy all those documents over to Evernote. Evernote will work it's magic, and make all the text in those images searchable. Any time you need one of those documents, just search inside of Evernote, and voila - it's there.
While a homemade scanner isn't the prettiest thing on earth, it does qualify as an exceptionally simple answer to a quite complex problem.