You will need at least one turntable and a mixer
Turntable - Technics 1200 or 1210
Vestax Pdx 2000
Mixer - Vestax PMC 05,06 or 07
Rane TTM56
Ecler HAK 380
Rodec Scratchbox
You can find turntables and a mixer on ebay or craigslist pretty easy and inexpensive used, compared to how much it will be new
the vestax mixers will be less money and are fine if you are just starting and pros use them as well. a lot of pros will use the other more high end mixers
you will probably want to get a pro x fader or
innofader to replace the crossfader. sometimes on ebay the mixer will already have one
the Qbert DIY 1 video is good and you can search youtube for tutorials
also Qbert has an internet scratch university, just google it
check out dstyles, ricci rucker, rob swift, rafik
i'm saying you only need one turntable and a mixer because you can use a tape deck, sampler, cd player or computer to play beats to scratch to. you can do more with 2 turntables, though