When the original Graphires were discontinued and replaced with the Graphire 2, I found a site selling them off CHEAP.
...approx $30.00 US for the 4x5 and approx $50.00 US for the 6x8.
I bought a few..
I used to have an old series 1 Intuos ( it used a serial port!
The first time I tried the 4x5" graphire for photo editing, I got rid of the large Intuos which had cost nearly 4X new. The size of the hand motions required when using the larger tablet was unneeded extra effort, and the precision is it offers at that size is never really needed for photo editing IMHO. On the very rare occasions that it is, simply zooming in and adjusting brush size compensates for it using a small 4x5" tablet.
I am a strong believer that for tablet for photo editing, less is more in this case.
The large tablets are more useful for drafting and digital paint applications.
IMHO the only sizes that should be considered for photo editing in PSCS is the smallest 4X5 and the 6X8. I use the 6X8 for a dual monitor set up. 4X5 is perfect for a single 21"Monitor IMHO.