We invest in numismatics and have a lot of very old and valuable coins.
One thing I keep on hand is a roll of Morgan Silver Dollars. I put them in the special casing from the coin exchange and give it to say, a big brother or sister, etc. They cost about $12.50 each when we got them and some are worth about $25 now.
I also like to give proof sets of the birth year. Some years are pricier than others but it is a nice gift as well.
My daughter received a couple of hand made blankets which were very nice and special to us. One family we are close to gave her one of the Dreamsicle figurines when I announced that I was pregnant and gave her one for each birth year up to age 7. Very nice. Ever since then, they have given her a special Christmas ornament for her collection.
Have fun!