I had to put my shelves over to the right (rather than centred on the wall) so that my shutter was still functional.
I am sure that this would be an easy project for someone handy and very inexpensive too! You would need to buy, then prime and paint some wood strips. Each shelf would use 3 - 48" (or whatever size you wish!) pieces of wood: a 2" x 1/2" piece for the back which is screwed into the wall, a 4" x 1/2" piece that forms the base and a 1" x 1/2" for the front ledge. After everything is painted, glue/nail the pieces together and attach them to the wall with plugs and screws.
Unfortunately, I am better at coming up with ideas for these sorts of projects than I am at actually completing them, so for me it was worth the $15 each to just purchase the shelves.