Buy most of your stuff from Menards, Lowes etc. that way you can get replacement parts for them later, most of the rv stuff is built light weight and odd sized. I would start with a Menards charge card so that you get the 5% discount, it will add up over the course of the project.
The Rv Specific stuff I'd get a Camping World membership, that way you can order specifically what you need and not have to design around some offbeat cast off that some Elkark surplus dealing bought in a pile so stuff at an Auction. If you go to your local RV Dealer they usually have free big RV catalogs for you to find 90% of the generic RV parts for sale nationally. Then order that part from Camping World.
Do I sound bitter towards Elkhart?
I have a 13' powered awning that only once I built a custom box so it could be recessed, and got it wired up, only to find out it extened 3' (a slide out awning) then the peice of shit, failed to retract 400 miles from home, I had to dissaemble the awning and cut the fabric from the roller to get home. After dissaembling it yesterday, it appears I had a prototype that the drive gear was just tack welded to the drive bushing together. Of course no warranty. Thanks Bobs RV surplus in Elkhart!
I have a stack of windows that were NOT reversible left to right as I was told, Thanks TNT surplus Elkhart!
I have a microwave oven that was new in a box, paid a good price for it at Trina's RV surplus.
when to use it after rig all together... Missing the rotator part for the plate thingy.. had to wait 3 weeks for part from manufacturer!
Bought a flat screen TV form TNT in Elkhart, worked great on the showroom floor got it all mounted and went to hook up the dvd player into the audio in to find out that the audio in jack don't work! grrr..
Then of course the f%^$#G! 450 dollar inverter I bought at Trina's after a week on the maiden voyage I found out the charger wasn't working, causing me to dissemble the entire bathroom to RnR it. Called Trina to tell her about it, she said sorry Its been over a year since you bought it, can't help you. I sent it in to have a new board installed. Robert at "One Stop" explained to me, that he can't rebuild that one 'cuz some one had already been in it and done some custom work on it.(it wasn't me) but I'm sure Trina didn't know about it either as she probably bought 20 of them at an auction. Another 1300 dollars later plus a new shower cuz the one I bought from Bobs RV wasn't removable and then reusable! I bought a nicer NEW one from Menards. Cheaper than one I bought at Bobs too!
Trina's guys also sold me an alum. aux gas tank for my genny, went to put a fitting in it to find out that the threads were stripped.
Be careful which hatch doors you buy, the company that made min is out of biz, I can't get a replacement for the one I damaged.
I still have some 48" shades, 2 black tanks a TV mount a whole bag of electric outlets and switches and a pile of other stuff I bought in Elkhart that I'd love to sell, It just didn't fit my application.
Rant over... be careful what you buy there, most of the time there is a good reason it's surplus!