If you're on a budget, pipe clamps are hard to beat. It's just a matter of buying, or scrounging pipe when you can.
I have the following clamps
2-10' 3/4'pipe clamps.
4 -1/2" pipe clamps 5' long.
At least 20 F-style clamps of various lengths.
4 sets of Bow Clamps, cauls.
A tip for the pipe clamps for panel glue up.
Use a 3/4" dowel run along the length of both edges. Apply the clamp pressure to the dowel and it transmits the force to the material in a more centered manner.
"The first thing you need to know, will likely be the last thing you learn." (Unknown)