Always fun to go to bike shops. I usually check them out when I see one on the road and have some time to kill. All the ones near me are clueless on the bmx side though, so I tend to stick to mail order.
Also keep in mind, it's going to eat up between $3.00 and $5.00 of gas to get to the bike shop in a car. That's a good portion of your shipping right there, plus you may save $2.00 per cable by getting it mail order instead of at the shop.
Not trying to talk you out of going to the shop, but unless you are driving, you could talk your parents into paying the shipping or something if you are paying for the parts and you don't have to take their time driving you around. You just setup the entire order, then have them pay for it via credit card in two minutes, then they are done.
Meh, go to the shop, have fun.