You let your fingers do the walking!
(Yellow Pages slogan)
Sounds like now, but it wasn't. You were restricted to your local area (unless you had access phone books outside of your area) and you had look under some headings which you wouldn't have thought of. Colostomy and Ostomy Specialists was one, but there were the fairly obvious Surgical Supplies (okay, not that obvious) and Mobility Aids (okay, no obvious ones. I don't remember seeing 'incontinence' as any kind of heading; you had to read shops ads for mentions, or just inklings, of inco stuff).
And, of course, you had to ring them first (unless you were in their whereabouts anyway) to see if they not only stocked inco stuff, but of what kinds (not all did pads, etc) and if they actually sold to the passing public (some only sold to trade).
And then, you had to make the trip and back, and sneak them in (stashed in a bush until parents in bed
).
All a bit daunting, costly and time-consuming, and (and it's a big one
) you had consider the shop's phone number showing up on the phonebill for whomever to query (cos no privacy of a mobile phone).
Other than that (which'd be mostly for AIO dispies), in the UK, Boots was a big stop for youth/adult plastic pants (their dispies were dire) or local shops for toddlers' pants.
When I first started out, at about 7, we lived in the local cornershop, so I swiped my pants from the shelf.