This depends on a lot of factors - where is the machine coming from? If the answer is Japan, it's going to cost a lot more than if you're buying one off of somebody in the US. There are also multiple means of shipping. I'm getting an IO board shipped from Japan right now via sea, and it's pretty inexpensive, but takes about 3 months.

It's shipping from Pennsylvania. I thought it cost about $400, but I wasn't sure.

Depending on who you're buying it from, your best bet might be shipping it via Amtrak. If you can get the owner to put it on a train on PA, and there's one that goes straight to Seattle, you can ship very expensive things for much less. This may not possible unless it's coming from a bigger city, like Pittsburgh or Philly.

I bought a Sega Astro City candy cabinet from Northern California, it ran about $150 to ship it to WA.  A DDR cabinet from there would probably be about 200 in shipping. I would estimate if its shipping from the east coat, a ddr cab would probably run about $300-$400 to ship.  If you are getting a frieght from Japan, expect to pay about $800-$1000 a cabinet.

I have been looking into this a lot recently. I assume you're hoping to get the machine on Ebay that's in PA eh? Good luck to ya.

Now then, I have been inquiring into the same thing and long story short, you're looking at a minimum of $500 to move the machine and pads. Usually this doesn't include pallet and crating fees. And to be perfectly honest, if the current owner of the machine is unwilling to pallet it for you, or take care of some other basic things, the fees only escalate from there. Because of these factors, I have resigned myself to only considering auctions from sellers who are willing to help me get the thing shipped, because if they expect to sell this to an out of state buyer, then sit back and not do anything, that will just cost the buyer a ridiculous amount of money.

Anyways, now that I've gotten that out there, let me offer you some suggestions. Call the Beltman Group (1-800-959-8880) and tell them you want to ship an arcade machine. They're relative experts at this and if I recall correctly, they're associated with North American Van Lines (a huge moving company). So, I'd give them a shot. They were the most knowledgeable and helpful moving group I was able to talk to regarding transfer of a DDR cabinet.

Good Luck.