Here's a few other things to consider:
First, you should do a search of eBay for all current listings for the IIGS to see what the current price range is. Then do the same search for Completed listings to see what recent sales went for, and look at each system that sold to see it's condition & what exactly was included. Keep in mind that on eBay, not only is the current competition important but, maybe moreso, timing is critical - you need to be selling on eBay just when some folks are desperate to get exactly what you're offering. I just saw today an item that was listed for one price, the auction expired, the same item was listed for more & sold right away at the higher price. Its all about the timing.
How quickly do you want to unload your's? If you're willing to wait, you can get a higher price. But if you're desperate for the money (or to free up valuable space at home, etc.) you will need to drop the price to reach all the chintzy buyers or resellers.
The ROM03 systems generally get more than ROM01 or ROM0, since ROM03 is required to run GSOS and the ROM03 boards came with 1.25 MG installed.
Take the time to CLEAN your system thoroughly and take good, clear photos to display. Most sellers on eBay just want to dump their items and heaven forbid they should clean them up a bit. Cosmetics DO matter quite a bit.
If you have the original boxes & packing materials, original disks and manuals you can command considerably more than if you don't. Serious collectors need to have the box, original packing and all the included paperwork. For example, a complete in-the-box IIGS that is in mint condition will fetch the most. The same but incomplete IIGS (missing paperwork & disks, for example) in it's original box comes in 2nd. The same IIGS in a retail box other than it's original box (that is, the serial number on the box does not match the serial number on the unit itself) is 3rd, and so on...
What does your S&H include? Mine includes the eBay handling fees, PayPal handling fees, packing materials & of course the FedEx or USPS shipping fees. Thus my S&H fees are higher than normal, and that limits your market. If you are willing to bury the high eBay fees (9-12% including the S&H) and PayPal fees (3%) into the price of the item, you're S&H is lower & that does have a positive effect on buyers.
Are you willing to ship outside the USA? If so, you're market is increased... but of course S&H is considerably more (you pass that on to the customer, one way or the other) but more importantly, there are a LOT of downsides to shipping overseas: length of time to delivery (so your buyer can slam you on your feedback), there may be customs forms to complete &/or fees to be paid, and there are more of the Nigerian Banker scammers out there to contend with. I restrict my sales to North America, which limits your potential market.
One final thought for now - if you list it as "untested" you might as well list it as "broken and does not work". Seems to mean the same thing on eBay.
I've been restoring/reselling Apple II computers for a number of years now, and I have gotten the full range of prices for IIGS units, all depending upon their condition, how they are outfitted and pure luck of timing. You've already seen the comments about parting your system out, but I watch these things very closely and I doubt you will get more by selling your system piecemeal providing your have an intact system in good condition and you take the time to clean it up & thoroughly test it out. And it takes longer to sell pieces. The market it flooded with IIGS base units sans keyboards, mice, cards, etc. People buying pieces are either looking to replace a broken piece or, more often than not on eBay, looking to build a system for cheap.
Ken
www.Apple2Online.com
(I still have my first "copied" set of DOS 3.3 disks... *sniff* - nostalgia!)
