I have my stuff many years ago. Polaroids and others film still available in the market, I just bought a used sinar from aloyyolaaloy, paid him 2x for what he ask, haha.
ebay has the widest choice, Linhof/Sinar/Toyo/Horseman/Speed graphic and others include china made cheap and good equipment.
Is better you joint the group RF to gain some experience before you start rolling.
I still use my 4x5's..though not on a regular basis...I just recently did a survey of an old government building with my Toyo...Nice thing about large format work is you can charge more for the job as there is very little competition...Chk my blog for a pic of one of my rigs... http://snakephoto.blogspot.com/2010/08/sometimes-i-have-to-work-with-real.html