Should I buy a carboy or a keg?

I'm shopping for another secondary fermenter. I plan on getting into kegging sometime this year. So, I was thinking about getting a used corny keg instead of another 5 gallon carboy. They're roughly the same price. And it will be one less thing I'll have to buy later.
I'll have no CO2 tank or dispensing gear. So, I would need to seal the keg with an airlock. Can this be done? Is there any reason why this would be a bad idea?

 

Are you planning to use the keg as a secondary fermentor? Only thing I can think of is that you won't be able to purge the air from the keg or get it to seal properly if you don't have a C02 tank.

 

Yeah. I want to use the keg as a secondary. I was hoping I could somehow seal it with an airlock. I've never actually seen a corny keg in person, so I wasn't sure if it could be done.

 

Without a co2 supply, you lose some cool things about the corny related to secondary - being able to purge oxygen, being able to jump the beer to another keg under pressure, being able to carb in that vessel, etc.

For secondary purposes, it still has two advantages over the carboy - it doesn't let light in and it already has handles. I would probably go with the corny.

 

+1
I never use my Carboy except for apfelwein