I'm getting my little guy in December too! Congratulations!
I'm in the same boat over crate/playpen, not sure which to do, so I'm doing both and we'll see what works better.
I got a crate from my sister-in-law's mom and I'm looking for a second hand playpen. There's no reason you should have to pay full price for either - these are things that people are usually willing to get rid of pretty cheap if not for free just to get them out of their basements! Try asking around to friends and co-workers and I'm sure someone will know someone where you can get them for cheap.