D and I were going to get married in a registry office. The only reason we didnt was that mum was dying and we wanted her to see one of her kids married with the whole nine yards. And we could afford to do it then because she paid for most of it too.
You can wear anything you want to the registry office, you can still say your own vows etc, you can have about 20 people there, so you can have close family and friends - which means that no extended family is going to be offended because you dont have to have any there at all. All you need is yourselves, and 2 witnesses.

I think it is just as special as any other wedding, they just dont make tv shows about registry weddings! lol

There is no reason you cant have some sort of reception after the ceremony. A ****tail party is often WAY cheaper than a full sit down dinner. You can see if you know anyone who will make your cake for you, that will save you about $1000 right there too.
My flowers were really simple too, but they still cost $900 - which is pretty cheap - but the less tables you have, the less you need centre pieces (again, ****tail functions eliminate the need for big sitdown tables.) Also, having only one bridesmaid and groomsman will keep the cost down too - only buying one dress/suit and one bouquet, etc.

Anyway, I know how stressful it can be - I planned my whole wedding in 5 weeks lol - so if you need help with anything, let me know Good luck and hang in there - at the end of that day you will wonder what all the fuss was about and just wish you had more time to enjoy each other