If it's just to digitize receipts I'd use a scan snap.
Damn why didn't I think of that...Look into Fujitsu scanners, they're more expensive but they're lightning fast, last forever, and scan directly to PDF. It's the initial scanning spree of going paperless that's the pain and it will take forever with a cheapie scanner.
This one comes with software.
The scan snap now comes with a plastic carrier pouch for scanning odd items, although it won't work on anything rigid.We use a Fujitsu S510, similar to this one on Amazon, and it works great.
The Fujitsu ScanSnap iX500 mentioned earlier is probably an improvement over our older model.
One thing we have found useful is to have the default folder set to one that is a shared folder on Google Drive (similar to a Dropbox folder). We can then access any of our scanned papers from anywhere we have internet access. It also provides a backup of the files.
We scan everything and end up tossing 90% of what is scanned. Most of our contracts, change orders, pay apps and wage reports are submitted via email.
One drawback to the ScanSnap is that it can only scan sheets of paper. We use our flatbed scanner a couple of times a year to scan non paper items. (fabric sample, OSHA cards, etc)