Congratulations on receiving your Amiga GIFT. The best place to look for classic Amiga parts IMHO is eBay, where almost anything you want is available. There are still a few suppliers around who stock new boards and upgrades for classic Amiga's. I can recommend AmigaKit as an excellent source, but there are a number of others.
There are also some excellent websites that cater for all things Amiga. (This site included of course).
Anyway welcome back to the family.
TrevorDick