When my sons turned 7 they decided they wanted a baseball themed party because they were both playing ball that year. The idea worked out well since their birthday is right in the middle of spring ball season. They wanted to have the party at the local park, which was good for me because it meant I didn't have to work like crazy on the house :) Several weeks before the party I started shopping around on ebay for prizes and other stuff. I snagged an inflatable baseball chair for a quarter and very low shipping along with twenty packs of baseball cards, also very cheap. I also found the baseball themed goody/loot bags extremely cheap. I spent under $10 for all of it. A few days later I picked up a 'pin the ball on the baseball player' party game for a couple of bucks. At the local dollar store I picked up a package of medals to also use as a prize and the table decorations. I went with plain red plates, cups and napkins with red plastic tableclothes. For extra decoration I used red, white and blue crepe streamers, which I strung from the rafters of the covered pavillion where we had the party.  About a week before the party I started work on a baseball pinata. I had priced them for about $10 through oriental trading but decided it would be fun to make our own and save the ten bucks too. I found directions online and it really wasn't hard. When we were done it might not have looked exactly professional, but had a blast working on it and the kids didn't even notice that it wasn't store bought.   I made the invitations on the computer and printed them out on cardstock. The invitations had a picture of a baseball player hitting a ball and inside the ball the words of the invitation were written. They read "Catch the Fun at Storm and Noah's 7th Spring Training Birthday Party" Report on...." and then had the time, place, etc. I was able to fit four invitations per page and then cut them using a paper cutter (since I can't cut straight with scissors :)  The day before the party I baked two baseball cakes using a ball shaped cake pan and decorated each with a #7 candle and each boy's name. On the day of the party we served the cake along with sports drink slushies. These were very easy to make (just freeze the sports drink until it gets slushy and then serve). The slushies were just right in our area because it's already hot this time of year. For games we played the pin the ball on the baseball player game and I gave out the inflatable baseball chair as first prize along with the medals I got at the dollar store for runners-up. Then we let the kids have a turn at smashing the pinata with a baseball bat (keeping the little tykes well out of the way). When it was smashed, everybody scrambled around to get the prizes and candy that came flying out. Since there is playground equipment at the park, the kids also got to run around and play some as well. After cake, we opened presents and then it was time to go home. Each kid received a baseball goody bag. Inside I had stuffed candy baseball bats (purchased at the dollar store), blue and red star shaped bubble bottles (left over from another event), baseball cards and miniature Baby Ruth candy bars. I had made labels for the candy bars using a desktop publishing program. The labels were really cute. They read "Thanks for coming to Noah and Storm's 7th Birthday Party. We had a Ball!" and had a picture of a baseball and glove. I also made new packets for the baseball cards that said pretty much the same thing as the candy wrappers and then put the cards in them and taped them up.   For the entire party I probably spent only about $50 or less and that included buying the ball cake pan for about $10. Everyone had a great time and really enjoyed the theme.