Shameless plug, but I happen to have a few goodies that could fit your budget in the classifieds section.
https://986forum.com/forums/boxster-cayman-parts-sale-wanted/85995-koni-special-active-h-r-lowering-spring-setup.html
You probably don't need everything, but I do have the sway bar setup that you could potentially benefit from.
Plug aside, The Radium King's recommendations are solid.