Go to East County guns, find one, buy one.  Gemtech Alpine with all stainless guts is a good standard, but the Mite and a few others are also very respectable.    
Fill out form 4, get finger printed at your chief law enforcement organization, in Grays Harbor that is generally the Sheriff, get a passport photo done, send in form 4 with a $200 check (Andy will do it for you) and wait.  The BATFE background check will take 5-8 months.  (First wait time for me was 5 months, currently I am waiting on cans purchased in June 2012 and December 2012.)  This is not a purchase for the impatient.  Best advice is to forget about it.  They will mail back your Form 4 application with a $200 tax stamp, Andy calls you, and then you go in and pick it up.  You can also create an NFA trust for about $100-150, Shannon at Brislawn Lofton can get you going.  If you need that data, let me know.  It doesn't add to the wait time, it just helps you bypass the fingerprint, photo, and LEO sign-off. 
Lots of very reputable can dealers out there.  Chip at Cascade Arsenal, Rainier Arms in Kent or Auburn (I think that is where they are), and East County Guns are where myself and a number of friends have made purchases at.
My suggestion to you is to buy one in stock.  Buying one that is not in stock will extend your wait time by 6-8 weeks, unless the dealer has already ordered one and they are just in the process of processing the Form 3.  There is a process to the madness.
Some of the lingo:
Can = Suppressor = Silencer= Moderator.  (Moderator huh?  Somehow appropriate.  

 )
Form 1.  You build the can yourself on a lathe, or out of pop bottles, or PVC.  Go through the basic process above of applying, and only AFTER you are approved and have the tax stamp in hand do you start the process of construction.  It will need to be engraved with a serial number per BATFE specs, so a pop bottle probably won't work. 

  Your cost is $200 for the tax stamp, plus materials.  Least expensive way to go, but you need skills and equipment.
Form 2.  Manufacture or importation of firearm, not used for cans.
Form 3.  Transfer from manufacturer/wholesaler to dealer form.  Usually takes 2-3 weeks to process, but times have risen to over 6-8 weeks.  These things are highly regulated and the BATFE wants to know where they are and who has them.
Form 4. transfer between dealer and end purchaser.  You, the trust, etc.
Form 5.  Tax exempt transfer form.  Used when you die, move, etc. 
Hope this helps.