Do you want a USB, SCSI, or Firewire scanner?
USB seems slow, I have some cheap HP 5300C and scans take a while on it... But I like this Umax Astra 6400 Scanner, and there is a 6450 that has a transparency cover. I know you can get it cheap, as on Umax's website it sells for $129 and that includes a firewire card for PC users (who don't have an Audigy...).
Firewire is quite fast
