[mo_focus]

well if you dont want to spend the money, just get your balance done first. that way you will know if its the tire or disc.

Also i had slotted disc and hated them. they would rust and go way off balance. so maybe you should just stick with the none slotted one this time

Bearings, well when you have your car on the jack, just spin them by hand and listen for the bearing.

So i guess, I would do the following
1- balance tires, while in the shop listen for bearing noise and order if nessasary.
2- drive the car again and if the vibration is still there it will most likely be your disc.