I agree with the consensus to start smaller.
120* (6x6) is a lot different than 8x10.
Neal is on the right track about an Omega "XL" enlarger. The XL just means that there is a longer chassis and therefore you can (eventually) make larger prints with less trouble. The advantage of a 4x5 enlarger, such as a D5XL, is that you can go to larger formats in the future, and they are usually built better than medium format machines. For 6x6, however, don't overlook am Omega B22XL (XL!!) if you come across one. If you have to pay more than $50, you've done it wrong. A Beseler 45 is not useless, either. When you find and buy an enlarger, make sure you get things like the right negative carrier, and lens boards.
I don't think anybody mentioned lenses. I recommend an 80mm for 6x6. EL Nikkor, Rodagon, or Componon.
*Not to be pedantic, but it's simply "120", not "120mm".