You can get lots and lots of stuff at Home Depot. Clamps, drills, drill bits, razor blades (by the 100, in the paint section), glue (Titebond, etcetera) tape, hand tools (screw drivers, plyers, allen wrenches), dremel tools. Did I mention clamps? You can never have enough clamps. Probably Xacto knive sets and blades as well.

On-line. you get the specialty stuff. T-pins, razor plane, slot cutting tool(s).

I'd probably guess that I got the vast majority of my stuff at Home Depot or the local hardware store. Probably 80-90 percent. Whenever I think "I need a tool to do ....." Most of the time, I think I can find it at Home Depot or the local hardware store.

The one tool I use a LOT, that I don't hear mentioned here.. is a file. My favorite is a half-round wood file, about 3/4" wide and a foot long. It cuts through balsa and ply fast. But still gives you lots of control. Handy, handy, handy. Say you cut a whole for a servo mount, and it's a titch too small. Quick work for the file. A knife will work too, but with a knife you could easily slip and cut a gouge in the wood (or your finger) and overdo it. A file lets you do a nice job.

My cordless drill has been super handy. Not the big 18 volt, they're kinda cumbersome. Mine a 14 volt unit that's a little lighter. And it has plenty of horsepower to drill through balsa and the occasional ply. Don't have to mess with tripping over a power cord.