I actually did just that to get my first (and only so far) machine. I sold off most of my action figure collection, some comic books, statues, and all sort of other stuff I'd collected over the years. Made more than enough to get my beautiful HUO RCT that I got for $2,500!
Best decision ever! It's AWESOME to watch the total go up up up as you get closer and closer to the pin you want. I had a blast doing it. I liked all that crap I sold, but I LOVE my pinball machine! I don't miss that stuff at all now, and I play my pin every day.
Good luck!