HELP!

So, we need some help.  We are considering getting another car.  We need one coming up here and started browsing this past week.  Let me just say car salesmen are really not my favorite people.   They really are as MEH as they're rumored to be.  And Brandon and I must look like idiots... do they really think we don't know that they are struggling?  

-That "this" deal will be gone in March, but wait they'll check with the supervisor to make sure it really ends this month... hello imaginary person on the other line... "you sure they aren't extending the deal into March, ok I'll let them know"... psshhh ya right.  

-Or we could give you this ____ steal of a deal with 3.9 APR financing but only if we sign tonight.  3.9 APR financing, right now??  Really?  

-Or "wow, I've been working here for a while and I've never seen him offer that price, it must be cause it's late on Saturday but that's a steal... wow I've really never seen that"

We're young but not stupid.  

We've heard that if you are a Costco member that there are Costco deals at dealerships... which no one can seem to make appear on paper cause the deal they're offering is lower than the Costco deal would be.  Then why can't we see the Coscto paper work?

Anyway, the plan is to "practice" this whole routine at a few dealerships that we don't want to buy from, and then go from there. 

 We'd really really love some tips... on buying cars, on financing, on salesman... Can you help?  We're looking at a Corolla or Civic or maybe an Elantra.