If you're going to consume the entire keg in one day/evening, go with a hand-pump system. Cheaper and more simple to use.
If you want to continue using the keg over several days (ie a weekend at a cabin), go for the CO2 dispense option.
More info
Cheapest way to go about it
Regardless of which method you choose, keep in mind one thing: the temperature of the beer is the most crucial element and the most common cause of problems (ie. foaming). Keep the keg at the optimum temperature and you'll be pouring great beer all night.