I don't think I'd be calling Tower asking them to sell me everything I need. However, let's not rule out input from others here. Lots of people have good ideas, it's difficult to think of everything, and getting input from others is the way we all learn. Having said this, here's how I would approach this.

First, let's divide this task into manageable pieces. There are 3 logical groupings, plane and everything that will fly with it, building tools, and field equipment. There will be some overlap between the three categories. Some people take the minimalist approach to things and buy as little as possible. Others seem to want to have one of everything. I'm somewhere in the middle.

Plane: This list is dependent on the kit, some include more than others.
Plane kit
Engine
Radio
Fuel tank and line
Foam rubber for fuel tank, receiver, and battery
Rubber bands for the wing
Wheel collars
Spinner
Wheels
Wheel collars
Covering
Prop
Glow plug

Building tools There are so many, where to begin? Paul Johnson (AKA caffeenman) has a great site with lots of information on this: http://www.airfieldmodels.com
Building board
Wax paper or something to protect the plans
Knives - xacto and single edge razors
Glue - Fast and medium CA, 30 minute epoxy, wood glue (I prefer CA and epoxy)
Metal straight edge (12" and a long one)
Square
Covering iron and heat gun (some consider gun optional)
Balsarite (fuel proofing and to help the covering stick better)
Sandpaper, sanding blocks, sanding bars
Misc clamps, clothes pins, t-pins, tape, etc
Drill and appropriate bits
Cutting board(s)
Needle nose pliers
Screw driver(s), allen wrenches, and wrenches

Field equipment Same here, the possibilities are endless. There was another thread on this recently, I should go back and see what I forgot.
Flight box (can be home made, kit, or premade)
Fuel
Fuel pump (manual is fine), lines, and cap for fuel bottle
Glow plug power (can be a 1.5v battery, glow driver, or 12v battery and power panel)
Glow plug connector (not needed if you go with a glow driver)
Glow plug wrench
Prop wrench
Prop reamer
Misc screwdrivers, pliers, and allen wrenches
Chicken stick
Spare glow plugs
Spare prop and prop nut
First aid kit
Cell phone
Cleaner (I use Simple Green)
Paper towels or rags
Spare fuel line


Things that are not required, but are should haves:
Battery tester

Optional:
Electric starter (I have 2, but almost never bring them to the field)
Electric fuel pump (not needed unless you run large engines with big fuel tanks)
Tachometer

Note, this list is not complete. Hopefully, others will point out things I missed. I really should write these things down and add them to the checklist that bubba and I developed.

Edit: Done for now, I need a break!