Close friend that use to be active on the forums linked up with Master P. He flew him out to LA, bought everything he needed to make beats, put him up in a hotel during his stay, paid for food etc.
From what i've been told, Master P is an extremely humble dude and understands. I've heard plenty of horror stories tho. Really boils down to the individiuals your working with and what they want specifically. In my bro's case, it was easier to have a place for him to go work on the tracks than doing the whole email thing.
Now a days, I'd side with caution in that type of situation. At any point and time they can recoup any money needed to get you there to work. If it isn't specifically stated in a contract, I'd rather work from where im comfortable.
Having to owe anyone anything isn't something i like hung over my head but thats just me.