If you're going to try to sell it, I'd list it as:
*Commodore Amiga 1200
*Extra external disk drive
*Extra 130MB HD ('Seagate Model ST3144A')
(Explaining that this is external, and not in a case - I wouldn't be happy if I bought a computer and found a hard disk hanging out the back in an anti-static bag!)
*Internal HD
(Double-check this first. Just because you have DH1 and DH2 it doesn't mean you have 2 hard disks - it could just be partitioned. There's probably a command that identifies how many devices you have attached to the internal IDE interface.)
*Clock/Battery pack
*Chip Memory: 2MB
*Fast Memory: 1MB via trapdoor slot
*Fast memory can be expanded to 8MB.
I've think I've found your memory expansion
here, you might want to confirm if adding more than 4MB will cause problems with the PCMCIA slot (as reddwarfer has indicated.) Google should help there. If it will cause problems, remember to mention it if you advertise it :-)