As you found out, samples don't always turn out right, and it's great to be able to "double check" their work.
As for the print run size - if you look locally, you should be able to find a good quality press that does gang run printing - basically printing multiple clients' projects together to save on overhead.
https://secure.wikimedia.org/wikipedia/en/wiki/Gang_run_prin...
In your case, the special card stock for playing cards might make it difficult to find someone to do this type of printing for you - but in your case, you should be looking for a specialty card printer - maybe even printing on plastic (not paper) - which would involve searching within a whole different industry all together...
My takeaway from this: if you care about impeccable quality, it's a constant fight to get it and keep it. No one will care about your product as much as you do.
Some things I found useful for these high-value offset print jobs:
1. Print out a hard proof (at full size obviously), and have multiple people review its accuracy.
2. Provide your printer with both a PDF/X file and your Indesign file. Use Indesign. Ask your printer if they have a preference for the PDF/X settings.
3. Provide all of the above to your print house.
4. Request, at the very least, an e-proof from your printer. This is generated after they push it through their processing workflow. If it looks good, your only other concern would be press calibration.
5. If it makes financial sense, schedule a press check. I believe we paid $100/hour for ours, but they would not usually take more than an hour. I'd usually ask for adjustments if they were needed, then pluck off a print that looked good and sign it. I'd take an identical copy for myself. They'd then use this to compare press output with during the printing job. If any part of the job came out like crap, I could use my copy to show how off it was and get a refund or credit on my next job.
You don't happen to know of any good printers in the Portland area do you?