That is a tight budget! Not sure about gift ideas, but I can tell you something that's virtually free that I used to do: I made the birthday cards -- very personalized -- and then of course had everyone in the department sign it. This was years and years ago when clip art was hard to come by, and the card was printed on plain paper & folded. After a while the card became the big thing people wanted go to the birthday "party" for. One particularly personal one I remember went something like this - it was for our computer geek. She still had it on her board a few years later when I left.

IF DATE = 010302
THEN DATE = LINDA'S BIRTHDAY
AND LINDA'S BIRTHDAY = FUN
SELECT: COMPUTER DEPARTMENT EMPLOYEES
OUTPUT: PARTY
HAPPY BIRTHDAY LINDA!
DonnaP99