Omega or Toyo Monorail 4x5
If you are not certain that you will do 4x5 for the rest of your life, you may want to consider a monorail camera, like a Toyo or Omega. You can probably get one for $200 or so on eBay. Whatever lenses you buy will be good for future cameras you may purchase - you just change the lensboard, if the lensboard of your future camera is dufferent from the Toyo/Omega boards.
You will probably end up witha folding camera but they are not cheap and I would not want to spend the $$ unless I knew I was going to stay enthusiastic about 4x5 format.
You will need a sturdy tripod.