Usually professors don't charge for lectures to other universities, at least I have not heard of such case. They may charge for lectures to commercial entities, but no, not to universities. The invitation to professor to present lecture at other university is a sign of appreciation/honor.
However, the good speakers are in high demand, so if you are not attractive destination for the speaker to come (e.g. low grade university inviting someone from well established university) the speaker will probably kindly decline due to lack of time. You have to understand - they get a lot of these invitations and will be selective where to go. But I am certain they will not demand payment.
Having said that, the usual arrangement for someone's invited lecture is the offer of covering the cost. Well known, respected and/or older professors may request perks, such as 1.st class airplane tickets (which may be more than you ever expected to pay :). I have heard for case, where professor replied "I will come, but I want 1.st class tickets", and the reply was "We apologize, but this is beyond our budget, so we thank you for your kind offer, but we cannot accept it."
Now, it depends on how eager the person in question is to travel. If you invite someone to EU from US, and offer them 2 days hotel costs + airplane ticket at an attractive location, many professors will grab the opportunity to free visit to Europe.
In some cases, the speakers will cover their costs by themselves, either because they have some kind of grants for exact this purpose (spreading the knowledge, etc), or if they are young, not very recognized in the field, and are eager to get invited talk on their CV.
Sometimes it pays off to invite the professor who is in town for some other event (e.g. conference, business meeting), then perhaps you can get away with only a bottle of wine and/or polite "thank you", but you also risk that he will not be available, since he has other work to do during his stay.