Question for people who know DMV TTL rules

[mdost03]

Hi guys, my gf and I are going to check out a car for her in the near future. The deal would be if the gf likes it, we would potentially trade her vehicle to the guy and make an even trade. Does anybody know what it would take/cost to transfer the titles into each other's names for TTL at the DMV? This is new to me and I tried searching around and some people say you still have to pay the taxes, but then somewhere I read that if it's an even trade, no taxes need to be paid? Her vehicle is an 03 and the one she would be trading for is an 04. Any help is appreciated, thanks!