The 2006 Ghosts started with serial number 200, but the first few were prototypes, and not sold directly to the public (given to a Lapco team - Blowfish IIRC?) - I think that went up to SN 204 or something like that. So take whatever the current highest serial number is and subtract 204. So my Ghost (#308) is about the 104th 2006 Ghost to be built. At least, this is what I remember reading on other forum threads at about the time I bought my Ghost.
EDIT: Ah yes, here
is some information on the matter. It seems the first 2006 Ghost had SN 201, and 201-204 were not meant for release to the public, so 205 would have been the SN of the first Ghost sold.
EDIT2: Also, serial number 308 was produced in late 2008 (I ordered it for myself right around my birthday in 2008 IIRC, so mid-September), therefore they only made 103 of them from 2006 to 2008. I'm not sure how many they have produced per year more recently than that but I don't imagine it's too much higher. If they're already at serial 500 I'll be surprised. I think you're over estimating how common these are, toymachine. ~300 or fewer produced in six years.