There are two ways to get RVs:
amiibo figures and
Welcome amiibo series cards.
The
Welcome amiibo series cards are
not on sale anymore. They contain 50 villagers from previous Animal Crossing titles that were not in New Leaf on release. The only way to get them is through sellers that are not Nintendo. Ebay and Amazon are good places to buy some. On Etsy you can find cards that are not
Nintendo made but still work. You can also trade for them in the
amiibo Card Post Office on these forums (
https://www.belltreeforums.com/forumdisplay.php?157-Animal-Crossing-amiibo-Card-Post-Office), or buy/trade for some on the
amiibo swap reddit (
https://www.reddit.com/r/amiiboSwap/). I cannot vouch for these as I've never tried them out before.
You don't need to be in possession of the
Welcome amiibo cards to get or own the items that come from the RVs. These forums have a place to buy and trade for items (
https://www.belltreeforums.com/forumdisplay.php?81-Re-Tail), which you can use either the forum currency or in-game currency to get. If you want the actual villager, however, you'll have to go to the Villager Trading Plaza (
https://www.belltreeforums.com/forumdisplay.php?85-Villager-Trading-Plaza) and work out a deal there. It is now not really realistic or possible to fully collect all the cards unless you are extremely rich or buy the illegitimate ones.
The
amiibo figures that work with New Leaf are listed here (
https://www.nintendo.com/amiibo/games/detail/animal-crossing-new-leaf-3ds) and will bring in an RV into your campground. A few RVs from a figure will contain a villager you can ask to move in, but not all will.
The
only card series that you can still collect and buy are
Animal Crossing Cards Series 1-4. They contain villagers that were in New Leaf on release. These cards
do not summon RVs nor do they have rare items that are only obtainable from them. You use them to get villagers to move in or to get a random item.
You will know which cards are RV cards and which ones are not because the ones with RVs have an RV on them.
I'm sorry if I seemed harsh/rude, I'm not trying to come off that way. I hope that this has helped, and if you are still confused I'll try to answer your questions to the best of my abilities.