If you're going to make them, I would just go with purple/red/blue/yellow cardstock and some patterned paper with the same colors in it and make 4x6 cards. Print up in a squiggly font the details of the party (probably in red/blue or purple ink color) and attach that with a ribbon? Maybe have the title be "A Wiggly Party" or "Get Ready to Wiggle!"
I've been to two Wiggle's parties in the last year and they just used the Wiggles party stuff you can buy at a party store. One did something really cute- she had Anthony's workshop set up with arts and craft supplies and the kids could paint, color, make a collage. She also did Music with Murray and the kids played musical chairs. She made her husband dress up like Capt. Feathersword- it was quite the sight!
