Disney's Idea of a 'low-key' wedding (which only allows up to 4 people) is still over 2500. We thought about it too. We are semi-local and ended up eloping in tampa with just the 2 of us. I actually don't think you would be banned if you tried it. If you found a semi-secluded place on property and did it quickly (mine was only about 10 minutes total and we had our own vows) you could probably do it. Actually if anyone asks just say you are getting married tomorrow at the beach and we are just rehearsing. Most of the cast members are maintenance and would not say anything, if they called it in it would take a few minutes to respond and by then it would be over.
Diagon Alley may work but I know from experience it can be PACKED with tons of people and extremely loud and may kinda ruin a really nice intimate wedding.
BTW- to all of the EXTREMELY RUDE people on this forum, your comments are not very Disney like. I realize that you believe this is against the rules, but condemn someone for wanting something small and special? UNCALLED FOR! If you can afford it, that's great, but not everyone wants to shell out money. We all know just stepping foot on disney property takes a huge chuck of money. Getting married in a public area after already paying for rooms to stay there is not the same jumping to fence to get a free ticket. People come here looking for Advice not TROLLS