My midwife also does a tub rental. Chances are if they are trained in water birth, they'll know where to get a tub.
My midwifery has tubs for home births that they give to moms to use. I would check with your midwife first to see if they have their own for your use.
Hey sis! Congrats on your decision to do a waterbirth. I have done an unassisted water birth and plan to repeat again. It was wonderful. You don't have to use a birthing pool but if you can find a family pool that is deep enough so that the baby doesn't surface before he/she is ready to be pulled from the water, you will be okay. You know how people hook those hoses up to their bathtub faucet to give thier dogs a bath? I would just use one of those to fill the birthing pool or use your bathtub (although it will be less comfortable and give you limited mobility.