Here are a few of our very favorite science-y things. This is not exhaustive in any way, but includes some unique resources. Any of these would make a great gift for a science kid (or grownup).
Matchbox theatres with insect haiku's and The Poetic Cell. From the brilliant Leafcutter Designs. $7 each.
These sent my kids over the moon. They loved them! And then went on to make many matchbox theatres of their own.
Science Embroidery patterns from The Floss Box. $2 and up for digital downloads. I will never look at viruses and bacteria and cells in the same way. A quilt with these could be kinda crazy, amazing.
Necklace kit of the solar system (to proportion!) by Chain of Being. $24.50. This kit has exactly what you need along with easy directions to complete this fabulous necklace. Some of the moms in my homeschool co-op made these during our group's space study. This was useful for kids and grownups to memorize the planets and their relative size and distance. Awesome!
Born With a Bang by Jennifer Morgan. $10. My kids (and I) loved this series of books. The rich, colorful images combined with the gentle voice of the "universe" explaining it's beginnings captured my childrens' imagination from the beginning. We reread them at least once a year as bedtime stories.