It doesn't work so well with the nearest shop being 40 miles away, but I used to run a small business as a side gig in an unrelated hobby. It was heavily service based, and additionally I kept the main consumables (eg. tires, cables, tubes, loose bearings) on hand. I did have a wholesale account, but only made orders every couple months as shipping on wholesale supplies is a killer unless you have large orders. As a result I ended up getting quite a few parts at retail pricing from the local brick and mortar, though it was only 15 minutes away. For something I didn't have on hand my pricing went something like this:
Lowest price, ready in X weeks, ie after my next wholesale order comes in.
Medium price, ready after the weekend as I typically swung by the hobby shop weekly anyways. It was unfortunate having to pay retail for the part, but I made up for it with the service cost.
Highest price, I'll go pick it up tonight, but you're paying for my time.
For the price conscious regulars or those with spare time but lacking the skills, you get the part to me however you want, I'll install it. I would charge my regulars a lot less for this than a new customer though because I didn't want to spend time running down warranty claims if something went wrong with the part.
I share the above concern that while doing quality work in a reasonable timeframe is entirely learnable, if you don't already own the tools you may have a bit of a learning curve.
After my father retired he simply opted to start volunteering at the local bicycle co-op, but then again he's on a pension and doesn't have any expensive hobbies.