Gho

Something to consider that I don't think to many people know about is finding a buyer for your vehicle yourself ... but "flipping the sale" through the dealer your buying the new Jeep at's books. This gives you the SAME tax break on the new Jeep but at the proper used market price - not the low ball trade value!!!
I did this when I bought my 2011 JKSU. I was going to trade my Pontiac Vibe in for $10500 (brutal low ball trade)... but while waiting for my Jeep to come in I heard about "flipping the sale through the dealer". So, I decided to advertise on the used market... I ended up getting $15700 for it!!! This not only got me the extra $5200 cash but also gave me the tax break on the entire $15700 off the new Jeep.
This process is apparently "typically" done if you know someone that wants to buy your vehicle (say your brother or neighbour etc..) then the purchase and trade in flip can happen at the same time. With my deal the buyer ended up getting my trade a week or two before my Jeep finally arrived. Luckily my wife and I work at the same school so we just used our second vehicle.

TheBeast

I always use Edmunds to get a rough valuation. It's a good starting point for prices on trades and new vehicles as well as good reviews. I"ve done well by just walking away, but that's because I don't rely on financing. It also took me about 4-5 years to find a dealership I like (Southbank Dodge in Ottawa) and was willing to buy from. They've also been pretty good on service - again, because I do my homework, I say things like "these tires are $x dollars cheaper at..., I'll give you some extra money for the relationship, but let's be real" (when they quoted me a $500 premium over the tire dealer). I'm happy to negotiate something that works for both of us, and we seem to have a good relationship now.