Buy whatever type of furniture does the trick, there's no right and wrong to it, but in general terms, the more you can isolate what your kit is sitting on, the better. Many mix up isolation with coupling. Spikes couple, sorbothane or rubber isolate. Spikes are generally there to help level a piece of kit (CD players and TT's should be as level as you can get them). Sorbothane turns vibrational energy into heat energy by absorption. There are many other DIY materials you can use too to help isolate, so building an effective kit rack on a budget is easily doable. I like the IKea stuff but avoid MDF since it has terrible damping properties. Chip-board is better, ply better still.