When I bought a 4X5 camera two years ago I looked for some b&w film. I wound up with a 25 sheet box of FP-4+, which was the most reasonably priced film of its type. Price differences exist for a variety of reasons. I remember when Kodak abruptly raised the price for 100 foot rolls of Tri-X. The price eventually came down.
My school summers were spent working in the Camera Barn stores in NY. The Polaroid SX-70 film packs had a flat battery built in. Where shelf life was concerned, the battery would not last as long as the film. If the battery in a pack died, the film would not eject from the camera. At the same time, if someone used up a fresh pack quickly, the battery would still have plenty of power in it. When customers left us their used packs, we would remove the batteries and hold paper clips on the terminals. This would be used to pop off flash bulbs. Some of the bulbs were pretty large so we had to be a little careful. There were rubber band fights too. We were young.
I grew up in The Bronx and we had a Korvettes nearby in Pelham Manor. If I ran out of D-76 or fixer, they had i . I still have a black plastic Yankee tank with a stainless steel reel which I bought in the early 1970s at the Alexanders store at 59th Street in Manhatten. Department stores have not sold these kinds of photo items for a long time. It is not realistic for small camera/photo stores to sell 4X5 film. My local camera store runs C-41 and still prints on RA-4 paper. They do great work. If I need things they don't sell I can get them by mail or drive up to Unique Photo in Fairfield, NJ.