I can't speak to shipping costs from Japan to the USA, but have had a number of bonsai pots and tools shipped to Canada --- through eBay vendors, directly from nurseries, the Tokoname site proper and some brokered by Ryan (mentioned several times in this string).
The shipping is always prompt, surprisingly affordable and packed beyond reproach. To Canada, a small pot (or two, if you combo up) runs between $10 to $25 for surface or $25 to $35 for expedited/air. The larger pots ship surface for between $30 to $45.
Customs and taxes are the wild card. There are no applicable duties on ceramics into Canada from Japan, but you may want to review US policy before placing an order.
three suggestions
a) look through the Tokoname site. Many of the production pots are beautiful and affordable.
The sooner you plant it, the sooner it will start to build a patina of its own. For example, the 472mm (18.5") version of this Yamafusa is listed at 16000¥ (US$165) --- even with $45 S&H, you're on budget --- or reasonably close to it.
http://www.tokoname.or.jp/bonsai/gallery/78f43.htm
There are many comparable items on the site. Even if you "ain't buying", it's a fun site to simply poke around --- as well as a good starting point for some perspective on the retail value on some of the more popular kilns and potters (over-priced eBay Bigei pots comes to mind).
If interested, visit "how to order" at the bottom of the gallery page --- they are a class act.
http://www.tokoname.or.jp/bonsai/gallery/gallery1.htm
b) email Ryan (his e-address is on his blog, already linked in this thread). he ether-prowls various Japanese nursery and auction sites on a regular basis and will keep an eye out on your behalf. He may not be able to chase down what you're looking for right away, but will send a photo and a quote (this may be an estimate if it's an auction item) if/when he does stumble across something appropriate. He'll also give you a reality check if the 'wished for' is impossible.
c) check those (reputable) eBay vendors on a regular basis. As you know they post new items often, sometimes daily. The "auction" items always give you some time, but a good "buy now" posting can disappear fast. No surprises there.
I edit here to emphasize "reputable". Most of the vendors will give you shipping options (surface, SAL, air, EMS), but a few only offer the far more expensive EMS. That isn't necessarily an indication of business practices 'untoward', I'm only saying to ask first if it isn't clear on their page.
Good luck with the hunt. Let us know how things play out.
