Ask around privately with some people you interact with on here. There are some widely known distributors with low prices...and horrible service. But they tend not to speak publicly about that. Ask some people "in private". As for tax and shipping: You'll pay the state income tax of the state the distributor is in if you go pick it up. Tax laws vary by state so if it's delivered with "no tax" it's worth looking into your personal tax responsibilities. Many places have free shipping for most Sterns and charge for JJP, but really it doesn't matter - just look at the total price. $7000 shipped is always less than $7300 shipped, even if you "paid for shipping".

And for the record: I've made several transactions with several big names, and can wholeheartedly recommend Automated aka Pinballs.com and Mad Pinball.