It depends on what you plan on doing with the scanner.
If you're scanning many photos, we recommend getting a Fujitsu iX500, Epson FF-640 or Epson FF-680W. We've tested these, and have scanned 2500 photos per day when them. You can often get the iX500 for a good price on amazon.com or ebay.com, and can resell them on ebay when you're done.
If you're scanning many documents, we recommend getting a Fujitsu document scanner, especially the iX500. These are fast, reliable and work very well with VueScan.
If you're scanning 35mm film, we recommend getting a used Nikon film scanner on eBay. These are the best film scanners ever made. They keep going up in value, so you can probably resell them on eBay for more than you paid.
If you need a small, light, portable scanner, we recommend getting a used Canon LiDE scanner on eBay.
If you're scanning film larger than 35mm, we recommend a used Epson Perfection 4870/4990/V700/V800 on eBay.