You said you've tried twice on Amazon right?
There is quite a nice selection of SoA material on there from what I see...
http://www.amazon.com/s/ref=sr_nr_scat_381142011_ln?rh=n%3A381142011%2Ck%3Askies+of+arcadia&keywords=skies+of+arcadia&ie=UTF8&qid=1332862329&scn=381142011&h=0cd1adbeba90627182ff17fd58670d7b8f817cf2
I'd take a look at the feedback of the sellers you have tried already and see if they've had problems in the past. It may also be worth looking into where the seller is located. if it's close to you, they may have a retail location.
The important things to check on these sites are a seller's feedback and make sure its very high or perfect and if it isn't perfect read the negative comments as to why cause sometimes people are just jerks that complain about stupid stuff like not getting exactly what they wanted cause they probably didn't read the item description properly.
~Also~ Check their shipping policies and make sure they ship to your location and that you pick the right methods.
If you do those two things you'll almost never have a problem with ebay or amazon.
I've probly bought around 100 items from those 2 sites myself and so far I've only had 1 bad transaction where I never got my item. Of course a couple months later i noticed their once high feedback rating went to hell and their membership was canned shortly after that. Unfortunately i never got my money back on that one but it was only about 20 bucks so not too terrible.
Anyway check out the link i sent. The items are most likely custom made but looked nice overall. You can try a 3rd seller but check their feedback and shipping policies liek i mentioned.
Good luck to you!
On a lighter note Skies of Arcadia was a pretty good game. I played through it myself over 5 years ago. I'm sure any big fan of the game would be quite pleased with your gift idea. Skies artwork is pretty cool. lol.