Paying For Pets In Adopt Me! Cash

So recently, I've been seeing some players put on their roleplay names or post chats within Adopt Me! saying that they'll buy pets in Adopt Me! cash. I even saw it on their trade history from their journal which they put the heading "they were paying cash".

I asked this one person today in the server of how much cash you pay for a legendary pet (unsure if this is for fly/ride or not because they kept getting their chats tagged when attempting to say the exact prices), and they said that a legendary pet costs 1000 bucks (assuming it's without fly/ride).

My main question is... How do you pay 1000 bucks? Like I know there's a cash register...but the limit is 50 bucks at maximum and you pay that maximum amount 3 times. Then you have to wait a certain amount of time to pay more.

I wanna do this, but how can I get that 1000 bucks immediately if I sold them my pet? I mean...can someone tell me (whoever has done this) how the exact process goes?

Thank you for your time ☺️💜