I've used pay-pal before. I never pay the full amount until I arrive, however, unless it's for an apartment or house I've rented before, and trust the owners. It's a shame AmEx traveler's checks are no longer used, because this would be the perfect time for them.
A wire transfer may also work, for perhaps half in advance and half on arrival.
I have used my bank or credit union here in the states to buy a thousand or so euros, and my husband and I divide it up as we travel, and your brother could do that as well since he's taking a larger group with him. I would insist, since it's MY money, that it's not in a purse or wallet worn in pants:
When I travel to Europe, I use a "neck wallet" that holds my credit cards/passport and larger amounts of cash, and it is worn under my blouse. After 10 years and multiple trips, no problem. In my day bag I carry enough cash to get me through the day.