Steph,
I recently purchased a MityVac for $50. It wasn't all that it was cracked up to be. I had to pump and pump to get the vacuum pressure up to an acceptable level. I probably just had a bad connection somewhere (leak) but never found it.
Being an impulsive individual, I found a Gomco (used) on ebay soon after and got it for $50, 25 more to ship.
GREAT DEAL and an AWESOME product.
Basically you hook the vac device to a bung with a hole in it or better yet they sell orange carboy caps that have holes in. They are a better solution as they go OVER the carboy opening rather than in.
Once you make a vacuum in the carboy to an acceptable psi....the CO2 will bubble right to the top. Keep that up until the bubbling stops and you are essentially degassed.
As I write these we are drinking a red that we bottled two years ago BEFORE I knew a lot about degassing. The CO2 is present, and while not that big a thing...certainly detectable.
Let us know what you decide on, or ask more questions. Many people here have been doing this much longer than I have so others can give your further direction I'm sure.
Darren