Optimal usage of resources - level numbers

I'm making a game that will have level selection (think of something like angry birds lvl selector ). So little box in which is the number of the lvl (1-20) and underneath a little box containing 1-3 stars depending on the score player has accomplished. Now, I can prepare the images in photoshop and import them as individual buttons, or I can create one empty box and have the game write in the number of the level within it using some specific font.

Tho, I don't know what is the right way? What is more thankful for the resources, and the "proper" way of doing it...

Thanks in advance...