These are the main tools that I used to build the trailer.  For around $900 you could buy a very similar setup.

I picked these tools based on their reputation and reviews. I’m very pleased with all of them:
Makita 5007F 7-1/4-Inch Circular Saw
DEWALT DW618PK 12-AMP 2-1/4 HP Plunge and Fixed-Base Variable-Speed Router Kit
Makita 4329K 3.9 Amp Variable-Speed Top-Handle Jig Saw

For welding these are my main tools:
14 in. 3-1/2 HP Heavy Duty Cut-Off Saw
Hobart Stickmate 205AC 230V Arc Welder
4-1/2 in. 6 Amp Angle Grinder

I really like this table saw because of the rack and pinion fence system.  It allowed me to quickly and accurately make multiple cuts:
DEWALT DW745 10-Inch Compact Job-Site Table Saw with 20-Inch Max Rip Capacity

These tools I mostly selected because of their affordability:
1/2 in. Heavy Duty Variable Speed Reversible Hammer Drill
DEWALT DW745 10-Inch Compact Job-Site Table Saw with 20-Inch Max Rip Capacity
Saw Horses
Framing square
Self Centering Doweling Jig

Jigs that I created:
Circular Saw Jig
Router Circle Jig  – This one is very close to the one I created.