Which reptile expo are you planning on going to?

They will have pretty much everything you need.

As for a tub set up, the lid should lock around all four sides. Using something heavy to hold it down sometimes isn't the most secure way, although I have done it successfully, I would not recommend it as a permanent fix. I am not sure how else you would do it though. Maybe someone else has a better way?

Do not forget that you need a thermostat with that heat pad. I would recommend heat tape instead. it is way cheaper and less prone to bending the electrical components which is a huge fire hazard with heat pads. If you really want a heat pad though, they are all basically the same and pretty much any brand will do the job.

If you are getting a really young BP, fill the tub. Make it crowded to give your BP some more security, even if you have hide boxes. This will help out with feeding and taming. Also, the reptile expo will be your best place to stock up on frozen thaw feeders. Usually they will be on sale, plus they are their to help you find the best size for your BP while you have the snake in your hands.

That is all I can think about now.