Like a gentle snow on a winter's day,
we're celebrating x's burrr thday
before the snow melts in the sun
come on over and join the fun
Also you can try to come up with something "wintery" that rhymes with her age.
There are some very easy recipes for making homemade marshmallows on the internet (I know www.moneysavingmom.com has one). If you need a cheap goodie bag idea, you could make your own marshmallows (even cut them into cute shapes or the # to correspond with her age) and put those along with a packet of hot cocoa mix (or loose cocoa mix) in a bag. If you wanted to go one step further, you could dip some plastic spoons in melted chocolate and let harden then put those in there too! The silver plastic spoons would be super cute for that! Afix with a bow that matches your color scheme, a little note saying "A treat to warm you after our snow-tacular party - thanks for coming (or something - you get the idea)" and a cut out snowflake. Love the party idea - I'm sure it's going to be adorable and fun!