Fingerboarding as a hobby is multi use. You can collect and trade them as well as use them for progression, and many people do both.
Professional grade real wood fingerboards provide the necessary useability to perform real skateboard tricks and allow you to grow you skills without the dangers inherent to real skateboards.

But where do you start?  If you havent ever used fingerboards before, consider getting something cheap.  If you have been using something cheap and it's time for an upgrade, consider a Spork!

Pro level parts can be bought together or seperately, but arguable the biggest upgrade you can make for yourself is to get a real wood deck. Real wood decks like the Spork decks are made with wood veneers layered in a cross hatch pattern to increase flexibility, flickability and strength.  After a good deck is purchased, my next suggestion is getting wheels made from real urethane.