As others have said, the small, personalized items are great (and pretty inexpensive). Utilize the discount stores/dollar stores around you. I've made a pin box for myself, my diamond, and my Secret Santa person one Christmas and I think for all three of them it cost me less than $15. I've also done the glass jar and made a candle holder/candy jar, or another idea is to get a clay pot and paint it, then get some marbles and put them in the pot (like dirt) and take some ballpoint pens and a few silk violets (or any other flowers you like) and wrap the pens with floral tape to cover the pen and hold the flower at the top, and you can make your own pot of violets that is a great desktop accessory (my diamond now has hers on her desk at school).
Making your own letters to wear or making a tote bag with letters are pretty inexpensive too.
I also picked up little lions and other cute things when I've come across them...one of the gifts I absolutely loved was my blue lion sippy cup that my diamond got for me from Walmart, or buying a 3-pack of wooden picture frames from IKEA (not sure if they have them in NC, but we have them here in CA) and paint those, then put stickers on them (or paint other symbols/words) before painting some sealant on the top.
Best of luck with your new diamond!