Houston Hobby to IAH

Hey guys! I'm currently booking a flight to and from Houston. I'll be meeting up with some guys at the IAH airport where we'll get our rental car and go on our half week excursion.

I fly Southwest for basically everything, and they fly into Hobby. They're giving me an insane round trip rate that makes me want to use them.

Anyone know the most affordable way to get from Hobby to IAH? I've read that the buses are only like $1.25, but may not be the best choice if you have a lot of luggage. I'll have a personal bag and two others, so i'm not sure if this is the way to go?

Dates are April 29 (Hobby to IAH) and May 3 (IAH to Hobby) – if that makes a difference.

Thanks!

Matt