Drewhosik,
What you will need to complete a kit varies from kit to kit. While some kits will have everything you need except for covering other kits will require you to purchase almost ALL the hardware. The only way to know for sure is to consult the kit to see what is needed to finish. You can do this by researching the kit on Tower Hobbies website where they will you what you need. For the 4-star here is what they list
Engine: 60-.75 (2-stroke) or .65-.90 (4-stroke)
Radio: 4-Channel
Servos: 5
Servo Extensions (12"): 2
Y-Harness: 1
Covering: Three 6-Foot Rolls
Misc. Items: 12oz. fuel tank, fuel filter, standard fuel tubing
Two 3-1/4" treaded wheels
One 1-1/4" tail wheel
One 2-1/2" spinner
4-40 x 1-1/4" bolt and blind nut set
I usually budget the same amount of money that the kit costs for the extras. So if the kit costs $100 a good rule of thumb is to figure that it's going to take an additional $100 to finish the kit (not counting engine or radio).
Ken