Age group(s) for this birthday party activity:
Preschool and Younger
Elementary School
Middle School

Cost of birthday party activity:
Depends on number of guests and how elaborate you get with decorations, food, favors and activities.

Birthday party planning information:
For our daughter's 6th birthday we had a Luau Party. For invitations we mailed a "message in a bottle" in a 4" bottle, with a map where X marks the spot, complete with sand and seashells. The guests were asked to come in "island wear" and bring the bottle to the party so they could fill it with "Sand Art."
Each child received a grass skirt and a lei when they arrived (parents also received a lei). We (Mom and Dad) had on our Hawaiian getups, too!
We went to our library and checked out Hawaiian, Reggae and Beach Boy's music to play and had lots of luau decorations.
Games we played: Limbo (of course), Pass the coconut (like hot potato), Pin the monkey on the palm tree, a pinata and swimming.
We had Centers set up for: Sand art, Sea shell/animal beads for necklaces and Digging for buried treasure in a sand box.
On our fence by the pool we had a sign that said "Locker Room" and we hung up plastic pails for each child. This is where they kept their prizes and favors during the party.
We took pictures of each child with our daughter in their luau attire and mailed it to them after the party.
As guests were leaving, we placed in each pail, a Thank You card which included a gift certificate for a free goldfish at a local pet store. This way the parents can decide if they want their child to have a fish.
Note: I called our local Pet Store and they agreed to donate the goldfish. So, I designed a gift certificate on our computer and had the manager approve it.

Other suggestions or comments:
Many of the decorations and favors were purchased from Oriental Trading Co. (a great source for party goods) We also used our computer and our daughter's artistic talent to cut some corners.