While it's thoughtful to consider giving thank-you gifts to your supervisor and colleagues, it's not always necessary or expected, especially for a large group of 40 people. As an intern, you are not obligated to buy gifts for everyone in your department, and it can be financially burdensome, especially if you have limited resources.
Instead, focus on expressing your gratitude in a more personal and meaningful way to your supervisor, as they have directly supervised and mentored you during your internship. A heartfelt thank-you note or a small, thoughtful gift that shows appreciation for their guidance and support can go a long way.
If you still want to acknowledge your department as a whole, consider writing a thank-you email to the team, expressing your appreciation for the opportunity to work with them and mentioning specific positive experiences during your internship. This way, you can convey your gratitude without the need to buy individual gifts for everyone.
Remember, the sentiment behind your appreciation is more important than the value of any physical gifts. It's the thought and sincerity that count most in these situations.