nanny-
I’m not saying you have to pay $500 in order to enable someone to keep Shabbos, but there are people who give hundreds of dollars of tzedakah to kiruv orginzations so that not yet frum Jews will be shomer Shabbos. Is this much different?
On that note, since you aren’t receiving more for your money with that $500 because you could fly on equally qualitative airlines for $500 cheaper, and the only reason you are spending $500 extra for El Al is to enable them to be Shomer Shabbos… can you count that as ma’aser?