While there certainly are less expensive sources for the various LED solutions on line if you're so inclined, I'll just mention a couple of our traditional model railroading suppliers who are providing the LED solution for building lights...
...by no means a comprehensive list. Just a few to help those of us who work with more traditional sources. BTW, we (LHS) provide these and other LED items to our customers. I'm sure other LHS's do, also.
FWIW, always...
KD