Follow the advice of Loren, PseudoRealityX and oilleak.
I worked a ride and drive event recently that was put on by Monroe shocks. It was amazing to see how OEM shocks with only 20K miles were so inferior to the aftremarket shocks.
For saving money check out ebay. Search Miata shocks and look at the deals.
Don't go wild on mods yet. The best investement you can make in time and money is on you. Run all the events you can. Ride with others, and let others drive your car. Learn all you can and have fun.