If you haven't been picking these up as they're announced, Amazon decided to finally give you a way to get all 25 with one click over at their 25 Days of Free page (amazon.com) - scroll down past the days to find the checkable list and "Buy selected song" button.
Oh, one more thing - if you're GIFTING MP3s, Amazon says that you can get $2 off with the code GIVEMP3S. Details about THAT over here.
I'm reasonably sure nobody here will have heard of Kaye Brewster, but I really like her. Maybe you will too. Her website can be found at http://www.polopop.com/index.html and she has quite a few mp3 files available for your perusal.