You didn't say what you want to do with your A1200. If it is just to run some games, you don't need the 3.1 ROMs, or to install OS3.9. The preinstalled OS3.1 should suit you fine for most things you want to run.
The 1202 w/4mb RAM probably just needed to be reseated more firmly as it could have easily loosened during transit. Hopefully that will get you back up and running.
As for the broken parts and bad luck buying on eBay, there is a very old saying when ever you buy from those you do not know and it goes double for eBay, "Buyer Beware". Ask before you bid, check out the seller's return/refund policy, check their feedback rating and comments. Many items on eBay that are marked "as is" are already broken or have some kind of defect that the seller already knows about, but conveniently forgets to mention.
I have been lucky in the hundreds of transactions I have completed on eBay, but have had my share of a few bad ones.
Unless you think you have been purposely been lied to and cheated, it probably isn't worth the trouble of filing a dispute. Get what you can from the seller and just move on. Lesson learned.
Oh, by the way, I am not one of those sellers that have ever screwed anyone. Almost all of my eBay transactions have been with me as the buyer and I have not received a single complaint from any of the people that have bought anything from me.
