Hi Mumraa
http://dictionary.reference.com/search?q=invite
To ask for the presence or participation of: invite friends to dinner; invite writers to a conference.
To request formally: invited us to be seated.
To welcome; encourage: invite questions from the audience.
To tend to bring on; provoke: “Divisions at home would invite dangers from abroad” (John Jay).
To entice; tempt.
If I get invited I dont expect to pay. I may offer but I dont expect to pay from the outset.
I think that as long as you make clear what your definitions and expectations are you will find that everyone will be happy. But dont expect invited people to be happy to just open their wallets happily.
FD