DOING MY FIRST TRI! THE SEAL SPRINT IN CORANDO,CA (I'M IN THE MILITARY) just a sprint,do not have any gear,going to rent a bike, looking for a wetsuit(used) and shoes no problem.I am an avid runner,and bike,pretty good swimmer.
Welcome to BT and triathlon! Can you borrow a bike instead of renting one? Also, be careful ... people go into this with a 'bucket list' item to check off and they get hooked Most of all, have fun!
Also, even if you're a really good swimmer, make sure you can do the tri distance in the ocean, preferably surrounded by lots of people kicking and swimming over you. Because that's what a triathlon swim is actually like.