Advice needed on RV necessities...

I have only 1 item in my camper that is absolutely "priceless" to me. It did not cost a lot of money, but it took me years to locate a new one after my old one broke. (that included the one I kept in the house too). New-fangled one just never worked like the old-fashioned style, but the old-fashioned style (new ones), were just awful. I raised so much of a fuss over a period of about 5 or 6 years, I thought my wife would kill me, because I complained so much about the "new" ones.

Then one day! There it was! Kind of like the "little black dress" in the Goodwill commercial! Yup, it was one that finally worked .. WONDERFUL! I keep it now, in it's own separate holder, I wash it immediately after use, and I protect it like it's the last one I'll ever own (it probably is, because finding a good one is really hard to find). And I use this almost every day when camping.

What is it? It's a good-old-fashioned potato peeler! All I can say is, get a good one! You won't regret it when camping! We eat potatoes with every meal, including breakfast (home made hash browns, and sometime home fries for breakfast).

NEVER underestimate the joy of using a good potato peeler!

Just get the basics that you know you will need, then spend a night in the driveway and make a list of what you wish you had. Then go to a close by campground for a weekend, and make another list. You can always make a run to home or Walmart if you need to. That should give you a good idea what accessories, tools, and housewares you really might find handy.

I just recently (last two years) purchased the whole inventory of camping accessories. I avoided Camping World stores as I presumed them to be overpriced. A trip to my local CW was on the itinerary, though, for those hard-to-find-elsewhere items. To my surprise, with a new Good Sams membership ($25), I received 25% off anything I bought. My best score was a new Marinco 50 amp shore cord (MSRP $300) on the clearance table for $125 and the additional -25% off.
The savings on the cord paid for all my purchases, including the Good Sam's membership.

If you are starting from scratch get ready.
White fresh water hose, water pressure regulator, water filter (optional).
Sewer hose (25') I have viper brand, also get disposable gloves for this task.
Power cord with different adapters depending on your setup (15,30,50 amp) along with a surge protector.
Wheel chocks. I have the x-chocks, these help with front to back motion in the trailer when set up.
Leveling blocks for side to side leveling.
If you have manual stabilizer jacks, a 18v drill with an adapter will help speed up the process.
You should have toolkit customized to your rig with a good breaker bar and maybe torque wrench for changing tires. An 8-12 ton bottle jack is a must.

Other items I have invested in are a ground mat for outside the door, camping chairs, other household items (silverware, cleaners, swiffer, etc) so I don't have to always remember them.

Some brands are better than others, just check the reviews or ask on here if you aren't sure.

Camping World has good quality products at fair prices. You will not go wrong buying these items at one of their stores or online. Any doubts check the reviews for the things you plan to buy on Amazon.

You need the sewer hose and the power cord and the white drinking water hose. The rest you can add as you find you need it after a couple of trips.

My must have items are a working fire extinguisher, a good first aid kit, and duct tape.

Welcome, and congrats on your new rig! Interesting question, and I don't have any hard & fast answers.

My 2 cents on your question: our solution is usually to go for midrange on pricing for those "smaller" camper items. The cheapest usually are cheapest - in the old-fashioned sense of the word. However, the most expensive may or may not be worth the extra money. If you have specific brand-name questions regarding, say, sewer hoses, you might do a search on this site for others posting about it. You'll probably get a range of opinions, but some people seem to swear by a particular brand name for some things.