any Flagstaff or Rockwood popup dealer should be able to order.
depends on what parts you need. many parts are available through the item's manufacturer, such as parts for furnace, fridge, stove, oven, a/c, microwave, entertainment system, tv antenna and so on.
if you posted where you are, maybe someone could recommend a dealer for you.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC