Tickets are non-transferable. Yeah, they are available on Craigslist or e-bay, but the people who sell them are scalping multi-day passes by selling them a day or two at at time, at a tidy profit to themselves, and it's illegal. Even if you don't have a problem with the ethics of that, it's kind of chancy, because they've been known to hand you expired tickets and then disappear with your money.
There really aren't a lot of options; you can get a few dollars off at most from Ares or
AAA, I think, maybe $3-5 per ticket? There isn't a big advantage to buying them one place or another-- might as well get them from Disney travel as anywhere else.
Costco does a fun pack with 3-day parkhoppers, along with admission to Universal, San Diego Zoo, Sea World... etc.... it's a good deal, if you're doing the whole So. Cal thing. We didn't because we just flew straight to DL without renting a car.
BTW, 5 days is perfect. Lots of time to see everything while still having time to be leisurely, and take midday breaks. You're going to have a great time!
