I just redid the suspension on my MY07 GT Wagon as I couldn't handle the ride anymore. Felt like I was on the Royal Show bouncy castle!
So I spent:
$600 Bilstein Struts and Springs from the Wheelpower deal on the for sale forum
$50 delivery to Perth
~$300 Front and Rear Whiteline adjustable Sway Bars
~$300 installation and wheel alignment
That's ~$1250 all up. Right in your budget sweet spot.
I can't recommend this low cost setup enough. All made possible with the cheap deal on the Bilsteins.
The ride is great...sway bars make a big difference...I can't get enough corners in my daily drive now...particularly love the rail crossing next to work that requires a serious left / right combo with max power coming out of the chicane
Ride height didn't change much at all so you might want to consider changing springs but that'll cost you another few hundred. On the comfort side...it's still much the same if not better with specB's. I found the GT OEM setup to be quite bouncy. The most noticeable difference is at very low speed. The original setup was a much softer on speed humps than the specB kit. At speed though, I find the specB more comfortable as it absorbs large bumps easily without the bouncy ride after the bump.
Started with a Gen2 Outback, then got a MY07 GT Spec.B Manual w Cat Back Exhaust and Verso Tuned, now got 2 kids and a MY07 GT Auto Wagon, Ultrex stealth back exhaust, panel filter, Whiteline Sways all round, Spec.b struts and springs and Kido-Tuned.