Guess you have figured out by now to wait, if you have to, to work with the one you trust.

"Sooo....Do I need to make sure I have an actual sales invoice sent?"

Yep, or the receiving FFL will need to determine "market price".

"Is sales tax required to be collected in Washington state on gun transfers, and how is it possible for the State of Wa. to require FFL to collect sales tax on a sale they didn't make?"

Yes it is.  It's the law.  And if the FFL in Washington state wants to stay in business, he'll follow the law. 

And "how is it possible?"  Remember the last time they had one of those things there called an "election"?  Well, those guys that got elected made it the law.  Want to get rid of the law?  Then elect different guys.

Hmmmm ....  That sounds familiar.  Is is possible that a certain Chief Justice of the Supreme Court of the United States of America very recently said something like that?  

Yes, it's all true.  Not only do they charge a handling fee ($25-75/ea) they also collect 9.8% sales tax.  Doesn't matter that you technically bought it in the state the B&M store was located.  WA state gets the sales tax on the TOTAL transaction.  That means the selling price, plus the 3% (if applicable) card fee, plus shipping, plus the FFL transaction fee.  Meaning the grand total will be grand indeed.  I bought a Sig .22 pistol for around $400.  By the time Cabellas put the pistol in my hands, the receipt was closer to $600, than to $400.

But hey, if any of that stuff worked to frustrate anybody F**ked-up enough to turn the gun on Kindergarteners, I'm down with it.  Although I admit, it's a poor substitute for good mental helath evaluations and counseling.  And stable families where breadwinners can pay for medical services.  Having a safety net full of holes pretty much negates any help you might find there.  Point is, the process you MUST conform to would just flip out an unstable person.  Why fix it, if it's working? 

Many states are passing laws to collect what is being called "use tax" on sales made outside the state, but brought INTO the state to be "used" there. I have shops in MA and VT and both are doing that. We have had several customers berate us for doing such and scream and yell. We simply tell them very politely that the state they live in has made the decision to do so, and if they do not like it, to express their anger at the ballot box, or find another merchant who does not CARE if they are audited by the state dept of revenue and are MADE to pay the use tax on merchandise they transfered but didn't collect......out of THEIR pocket. I know it ain't gonna be me!

my tax lady told me that the use tax is on stuff that I buy out of state for my own use  since there was no tax paid when I bought the item(s)

In Wisconsin an individual is supposed to collect either sales tax on sales or consumer use tax on items purchased for personal use.

Quite often, the buyer SAYS they are going to find another dealer who isn't going to "rape" them and collect taxes. I invite them to do just that, and MOST often, after an hour or so, we get a call from the buyer telling us it is coming to us after all. It would seem that they either found another delaer who charges higher transfer fees or what not, but they almost always come back, we collect the tax and our fees, and they go on their way. It is, and should be, all about the bottom line to the buyer. But, it seems that there are people who just like to make a spectacle of themselves.

Gee I must be lucky I get mine transfered for $20 a shot without any worries--he might be missing on this I am not sure but I hope not --he is  good guy that treats me well and even though he has moved 35 miles away I still do business with him for that reason

Yet another way I seem to be blessed and lucky

BNP Hunter if you are a WA resident and your FFL isn't collecting the sale tax he is not following the laws of the state.  The 20 dollar transfer fee seems to be about the going rate for my piece of the state, but the 10% tax is the rate for the whole darned state.