1. Is it legal?
Against Jagex rules, but I don't believe it's
illegal.
2. Is paypal hard to put on a website and cheap? (you know, to sell the money!)
Wouldn't know.
3. Do Jagex shut down the Servers? (hosting or whatever i don't know)
I bet they could, if they wanted to, but it probably wouldn't be worth it unless the site is responsible for a lot of the Real World Item Trading going on.
Just be safe and host your own server.
4. Is it worth it?
Depends on how much time you wish to invest in it.
5. Can i get into real trouble for it?
Highly doubt it.
6. Are you against it (srl) Because if you are, i won't do it!
Probably not, unless you use Level 3s/RSDemon to go about getting the money.
7. And finally, can they track your credit card or something and get you arrested or something wild like that ROFL
