Hooah! Heh, hunting down hard to find and previous missed out limited goodies sometimes does bring joy when you finally able to obtain through the power of the internet. I do admit it does cost a lot of money. To me, keeping a good patience mind eventually will get you the best price rather spending triple.
I'm sure majority would go and search at eBay. Well, its true that we could find plenty of limited goodies there. But for book publication limited released toys are different especially Gundam plastic kit. I myself rarely able to spot the right price and sometimes require to bid for it. Plastic kit never worth your time on bidding. Reason is simple. We cut, destroy, modify, assemble, and paints. You can only go for either the sellers sold them for a right price or bundle them in attractive sets for bid.
Another problem I am facing with eBay is using the search engine. They rarely get the items right occasionally and had to spent more time checking through some discover sellers store for possible items. Of course, every time I got were ridiculous price range.
Luckily someone introduced me to check out Rakuten. It does have similar eBay shopping like, but almost all items that sold over there are entirely from Japan instead. The price is good and sometimes you get promotion on reduced shipping. I recommend readers to check it out if you look for any possible limited stuffs that can't be found on eBay.