Congrats on your first steps toward cosplay.
Things you want to consider when picking material:
-Weather. You want to use rubber? That's gonna be pretty hot. Hot and sweaty.
-I might suggesting reading up on the materials you're considering. See what experiences cosplayers are saying about working with the material. You don't want to put all your money toward a base material you can't work with.
-Also consider what you have to add on. How will the fabric you're getting for the details look against the rubber catsuit or the dive suit?