Well, the nice thing about having some 'freeze dried culture packets' is that you can make it up when you want it, and do not have to 'care for' the grains on a daily basis (or every few days, depending on how you brew your Kefir).
So they are nice to have. I have a box of Kefir and Yogurt 'starter packets' in my refrigerator (they keep up to a year from date) if refrigerated. They are a nice back up and the yogurt is a nice 'change' from all Kefir, all the time.
Regarding obtaining Kefir Grains. There is a link in several of the Kefir threads about looking up someone in your state, other than that, several mom's here have Kefir grains and ship to other moms for just the Shipping and Handling.
I'm currently super low on milk grains and it will be weeks before I can do another ship out. Go to the 'Got Probiotics - Kefir, Yogurt, Other Jan.) thread and ask if any mom has spares. I know that Ruthla mentioned she wanted to ship some. I know Gale Force usually has lots of extras, but she might be low as her DH is doing a dairy elimination and so her 'stock' might not be up enough to ship out.
Gem Cultures (you can google it) charges like 20 bucks, PLUS an $11 Shipping and Handling fee for the entire order, whether you just get Kefir grains or a bunch of stuff, so you can be assured the S&H fee us mom's charge (varies between 3.85 and 5.00) is worth the wait!