I factor in travel costs and time in searching for parts versus ordering online.
I don't find it cost effective to go to store to see their stuff then go home to order it online. If I am already at the store and they have what I need and the price seems somewhat reasonable, then I can take the plunge. But in the past 8 years I've typically lived in scattered rural campgrounds so I wasn't near major shopping. RV dealers and parts can be hit and miss in certain areas.
When I first started traveling in my RV with dog, I often stopped at CW and planned them in my routes as a rest stop. Typically I could walk my dog both outside and inside, very handy on a hot humid day. I could look over their parts and pick up what I needed. But the 3 tiered pricing left me confused and later on I discovered pricing was better online so I stopped going to their places.
One place where I needed a semi critical part, I ended up traveling to 5 different RV places and over 140 miles in assorted directions trying to find the part. It was a 30 amp RV plug! I had no idea this wasn't a standard part at least at the RV shops I visited. I did finally pay a fortune to buy one at the last place I visited. He had only one in stock! I was new to RVing at the time. Since then I began looking online for parts as that frustrating day was an eye opener for tracking down parts.
I have mail ordered from Camping World, but it's a huge problem in that if they deliver to the campground, then they inundate the campground with a ton of advertising mail with my name on it. It takes several phone calls to them to stop this practice and the campground was seriously annoyed as they didn't provide mail service but didn't mind campers getting parts delivery but they grew to hate Camping World for their massive frequent junk mail outs.
In store versus online...
My biggest problem is I am so darn picky and often the online shopping will allow me to find the "just perfect" thing versus the store which may not carry all the varieties. Also online sites may offer up newfangled stuff that isn't in the stores but is rather handy. Many times the online info will be better than the info available in the store unless one can tear open the package for inspection.
What I don't understand is that with all the mail order opportunities for shopping, why traffic is perpetually congested? :