It's not actually quite as bad as it appears. First place to make a saving, is to buy a bike that's near the place you're going to ship from, and I would strongly advise using Aladdin Freight, in Oakland, near San Francisco.
Next, get a good deal on the bike in the first place. Were you thinking of doing the deal yourself, in person, in the States?
What bike are you looking for?
I have found that one of the best ways to find bikes, is by using a website called CraigLook. This searches every craigslist site in America, and you can search within certain distances of a specific place, and limit results by price etc.
Craiglook: Craigslist Search
Then make sure you declare the purchase as a 'sensible' value. This may or may not, correlate precisely with the price you paid.
Surprisingly you can print out a bill of sale yourself, and sign it as the buyer, and this is an acceptable document for import purposes.
As a guideline, I might suggest this: Search and search for the bike you're looking to buy, and make a note of the cheapest price you ever see for the year and model you're looking for. Say $3000 as an example.
Then create the 'Bill of Sale' document, and fill in a sale price of about 30% less.
In our example, $2200 or so.
Something I thought would work, would be to write the bill of sale, naming the bike as 'Non-runner, sold for spares or repair. Sold as seen, no warranty implied or given'
Maybe remove the CDI or something in case someone tries to start it.
Just a suggestion, I'm sure it would work.
Then the shipping cost is actually recorded as less. I'm sure that most companies class a big chunk of the costs as paperwork or admin or something, and that the remainder is used to calculate the import VAT etc.
Does this help?
I'm in San Francisco this summer, and can help with anything you need.
What are you looking for?