this is purely guesswork on my part. i haven't done any fact-checking, so don't take my theory as gospel.
it's almost certainly less expensive for any business the size of Joann's to sell online, directly from their warehouse(s). it's also possible that at that tier of the business' structure they have data showing which fabrics are "moving" and which are not as popular in the shops and, therefore, "getting dusty".
my guess is that they put things on sale via the internet site in order to clear them out and make space for new products. or as a promotional strategy to keep the brand visible and popular among a broader spectrum of the customer base.
have you ever looked at the fine print flashed on the bottom of a TV ad for a chain restaurant? they'll advertise a special to the whole country. the fine print says things like "at participating stores." or "prices may vary." so, you go to your local Olive Garden in search of that bottomless bowl of pasta, only to have the waiter look at you as though you just landed from Mars. :lol:
in my own experience, whether or not a local store will honor an online price varies from store to store. Our local Papa John's Pizza, for example, will honor any PJP coupon - even if they didn't know about them. (our manager says corporate drives them crazy doing that. :lol: ) the Hancock's nearest me will do the same when it comes to online vs. in-store.
i can't address the nearest Joann's, specifically, since i'm usually too lazy to drive the extra two miles down the road from the Hancock's or LQS. :lol:
try this to see if it's a system that works for you:
(1) calculate the difference between the online price - with shipping added - and what you'd pay if you went to the store and found it wasn't on sale. (don't forget to factor in the intangible value of shopping in your fuzzy slippers. :lol: )
(2) if you save money, buy it online. if not, and you much prefer to shop in person anyway, then make the trip to the store.
:-)