Baby on a plane

Looking for tips here...I'm planning a trip to Texas to see my little brother. My daughter, 1 and a half year old Glynis, will be travelling with me, as will my mother. Here's the question...I have the option of buying the baby a ticket or not. She's under 2 so I can save myself a few hundred dollars if she rides in my lap. Then there's the car seat situation. It'd be nice to bring it with us and they'll probably charge something if I check one in.
I haven't flown with a toddler in many years, but I flew with the boys quite a bit when they were little. I don't remember so well these days. I'm looking for answers again! Please add your little chirp below.