Saving $$$ by turning down the thermostat

My sister is getting married this year.  I'm excited.  She's the youngest.  She's the last one.  I'm a bridesmaid---no matter that I'm married with kids---I'm a maid!  It suddenly occurred to me how much her impending nuptials are going to cost me.  Yes, ME!  Here are the expenses that I've come up with so far as minimums:

Dress: $200.  That's how much the one she initially picked cost which was subsequently vetoed by our other sister who is in the wedding.  I'm guessing the final choice (I think it's final?) will be $150 plus alterations.  Nope, neither one of these are the dress.

Shoes: $30 
Shower gift: $50-100 (this is my baby sister after all)
Wedding gift: at least $100
Shower expenses: ??? The bridesmaids are throwing the shower.
Flower girl and ring bearer ensembles: ??? Chances are that she'll ask Red and Tom Thumb to be in the wedding.
Babysitter: $75-100.  We're paying to plate a meal for our babysitter at the wedding so she can drive the kids home and put them to bed so we don't have to leave the reception before 8PM.

I'm guessing we're going to be spending somewhere between $500 and $1000 on this wedding.  Where is this extra cash that we don't have going to come from?  

My first brainstorm is turning down the thermostat.  I'm naturally cold so I like the thermostat at between 68 and 70.  Can I turn it down and be comfortable?  And if so, am I actually going to save money?

I tried it out yesterday morning.  I put on a sweater and turned the thermostat down to 64.  Initially there was no real difference.  By the end of the afternoon, I was a little chilly but doing okay.  Last night I slept with a sheet, a thermal blanket, an afghan and the comforter.  The verdict: I survived.  But will it make a real difference monetarily?

I found a website run by Duke Energy that has an online thermostat calculator.  It's intended for Indiana residents so I knew it wouldn't be an exact calculation, but I figured it could give me a ball park estimate.  I used zip code 47906 as my bogus zip code to get it to work.  You essentially describe your house (i.e. size, number of rooms, when it was built, etc.) and its heating system and it estimates what your savings will be based on how many degrees you turn down your thermostat and when.  Based on my home's thermostat settings previously being 68 degrees, it estimates that if I turn my thermostat down to 64 I'll save between $153 and $255 annually.  And voila --- there's my bridesmaid's dress!  Now I just have to dig out my sweaters and figure out where the rest of the cash is going to come from...