Some fabrics seem to have very limited runs - Alexander Henry and Michael Miller are two lines that come to mind.
If you see one of them that you really love, by all means get it while it's available.
You may or may not ever see it anywhere again.
The suggestion to get a coordinating fabric with the one that's bewitching you is an excellent one.
Fabrics "on sale" are my downfall. Full price LQS fabrics - I have LOTS of self control with them.