In addition to the camp fire program at Fort Wilderness you can also have a private hay ride which is what I did for a Welcome Party. It cost us $200 and the wagon holds up to 30 people. Not sure if that's still out of your price range, but it is still relatively low cost in Disney terms

Our guests loved it!
Here's some of my posting on it copied from my TR:
Here were my invitations that I made for the Welcome Party:
We took the bus to Fort Wilderness and then transferred to one to head to the area with the campfire program. The guys were already back by Pioneer Hall and were trying to decide if they were staying there or if they would come up to meet us. We got there before the movie while the ranger was leading the sing-a-long with Chip and Dale.
We didnt stay here too long. I think it would have been much better if they would have gotten to the singing, but the ranger was doing some banter back and forth with Chip and Dale and this was kind of overdone and her voice was a little irritating. I also would have loved to see the movie that was suppose to play a little later too. Monsters, Inc. was going to start right before we left for the hayride. The campfire program is nice and I think if you went just for the movie it would be better. They had campfires set up where you could roast marshmallows which would have been yummy! If you dont have kids I suggest skipping the sing-a-long part and go straight for the movie.
When we got to Pioneer Hall it was nice to see that a lot of our guests had already arrived. This was wonderful because we hadnt gotten to see everyone yet.
The wagon then pulled up and they said that we could start loading.
The hayride was a lot of fun especially for the kids. It was a nice peaceful retreat compared to all the running around that we had done. Also, it was the first time we had a large group of everyone together since their arrivals in Orlando. We spent quite a bit of time in the woods and they pulled on the beach where we could see the castle and Space Mountain (sorry about the quality of the picture)
The private hayride was a lot of fun and was an affordable option for a family friendly welcome party

We went this route since we couldnt afford to add a huge event, but everyone seemed to enjoy themselves and it was something that no one expected out of Disney. The total ride lasted almost an hour. I originally thought it was only supposed to be 40 minutes, so that was a bonus. They took us through a large area of the campsites and up to the front by all the stables too.