A basic rebuild with new bushings and joints is probably the safest approach for good peace of mind. $200-300 for this.
I'd add the TVS front sway bar, $330 or so.
That puts you at your $500 low level limit.
You could also maybe add a leaf to the rear while the springs are out for bushings (free to $100 depending on source) and/or add the rear sway bar ($350). Since you are not stepping up the spring rates, get over the counter gas shocks for $25 each. There is your grand budget for the year.
Don't forget that you need a radial friendly alignment too.
After that, you can then piecemeal the TVS system into place as your budget allows.