When I lived in Michigan, I could get applewood and cherrywood chips at Menards, where the charcoal and hickory chunks were.
However, if you have an orchard nearby, ask the owner what they do with the wood left over from when they take old trees out of production and replant.
My guy gets his from GI Joes stores where they sell camping, fishing, skiing, etc. stuff. They have a huge section of BBQ related goodies. (And some of the best Creole seasoning ever, KickAss something I think it's called, but it's only out around Christmas time.)
But I'm sure the wood chips are sold in most places that sell BBQs, like Home Depots and Targets, etc.
If you are up North some where is the US, you may have local Cider Mills. If so, give a few of them a call. A number of them will sell their wood at a major discount compared to on-line or other stores. Casper
Funny story. Yesterday, my Chef told me had spent his day off trimming his Pecan tree. I immediately perked up, and asked him what did he do with the wood? He laughed, and said the big stuff was going into his fireplace, and the smaller stuff went to his neighbor for smoking.
Locally, I've only been able to find applewood chunks and chips at Barbecues Galore. If you just need chips, you should be able to find them at Central Market, Academy Sports, and even sometimes Kroger. Of course, there are tons of places to buy them online. Hope this helps.
This time of year it's easier to find wood for smoking - at least in these parts. I've seen applewood chunks/chips at Kroger and discount stores like Walmart.