hey! that is awesome about your friend... i just had a friend who had been reserved about the whole greek thing before just accept a bid from my chapter on friday... i'm so excited to call her my sister
nationally, adpi's are allowed to wear letters as soon as they are new members, though i *have* heard that some chapters prefer their new members to wear adpi rather than the greek letters at first... the only thing that is absolute is that new members cannot wear or display the crest/coat of arms until they are initiated. so anything else should be okay! the best place to get official adpi gear is from giftmart, which adpi runs, and from which part of the profits go to our international philanthropy.... the address is
www.adpigiftmart.com so check that out
anything with violets, or azure (light-not navy!) blue and white, or clasped hands, or diamonds (like this: <>) would make a nice gift! also you can't forget lions, i have so many stuffed lions i don't know what to do with them though, so maybe something unique with those types of things, or maybe something with dg and adpi colors or symbols, like a frame and you could put a pic of the two of you in it? something that is common on my campus for friends in different sororities is for a friend to make two sets of letters, her own and her friends from the same fabric on the same type of sweat shirt so that you can match
also you can find different items and fun stuff on the other greek gift websites, such as greek gear express, frat row, collegiate gifts.com, campus cargo, sorority heaven, etc, etc, etc... if you do a search for key words including adpi you should find tons of stuff... congrats to your friend!