Elope!
A daughter of a friend of mine was married last year and she managed to do it all within her budget. She kept it as informal as she could, hiring the local village hall, getting help to do the catering - bufffet style.
Her mum made the small floral table decorations and her friends helped make the bunting. She printed out her own wedding invitations.
She wore a second hand dress so didn't spend a fortune on that (she looked absolutlely lovely!) and the men didn't wear tails so nothing to hire etc. They even bought antique wedding rings saving money there too.
For the after reception dance there was a group that played barn dance type music and there was a 'caller'. It was very sociable and everyone of all ages joined in.
Altogether it was a lovely, happy, family occasion - it didn't cost a fortune and all the guests had a lovely time!