it really depends on you and your brewing. i would say that if you intend on brewing a decent amount, and want to be able to drink multiple beers without drinking 12 oz of each of them, then kegging is definitely worth it.
if you plan on just doing 5 gallons at a time, doing the next batch as you are finishing the bottles from the previous batch, then don't worry about kegging, as it isn't monetarily worth it for you.
for me, i don't drink nearly fast enough to use bottles, and i like to brew. i started with 2 kegs and a 20 lb co2 tank i found for a good deal on craigslist. now i have a 6 keg kegerator and a 50 lb co2 tank. i have 5 beers and root beer on tap. and at one point, i had another two beers in kegs conditioning, waiting for spots in the kegerator. that is how slow i drink. i still have 2 beers in the kegerator that i brewed in early summer. haha.
also, after reading about people going to the hospital for carboy wounds, i've since moved back to a plastic primary bucket, and instead of a glass secondary, i secondary in kegs after a 2 week primary.
i've also transitioned to co2 transfers wherever possible. i still use carboys for my meads and in the future, wine, and intend on racking with either co2 or nitrogen, if i can get a nitrogen setup in the future.
so you know though, the costs continue to add up, even still. just like what others have said, i thought i would be satiated with a little, but now have 25 kegs, 5 co2 tanks, beergas tank, 2x 2 pass cold plates in jockey boxes, just bought a 6 pass cold plate so i can make a larger jockey box, etc. you don't have to go that far with your purchasing, but getting started will make you want even more... haha. don't forget that craigslist and ebay are your friends if you can shop patiently and intelligently.
