I think Mobile Ed works in your state. Their address is www.mobileedproductions.com/search.htm
I've had good luck in finding various assembly options by searching Yahoo with school assembly and then the state. It's amazing what's out there.
Most Irish Dancing Schools will have their dnacers put on a performance, for a small donation. It gives the dancers practice performing, and Irish dance is very entertaining to watch.
We had a free assembly put on by our local Coast Guard station. A helicopter came and landed at the school! I don't know if there's any local armed forces in your area, but it's worth looking into.
Check with your state to see if they have something like Young Arts of Massachusetts, or and Arts Alliance. We do not have a PTO, but we have what is called a PAC, Parent's Advisory Council. We work as a PTO, but we are mainly responsible for bringing enrichment programs into our K-8 school. We also, offset field trips, etc.
We get most of our enrichment programs from the Young Arts group. A couple of months ago we brought in a fabulous performer, Billy Jonas. He travels all over. He was terrific. In the four years that I have been Co-Prez, this was the first time that all the teacher K-8, loved an artist, as well as the students. My daughter who I have had to quiz in the past about how she felt, came home talking non-stop about this artist. It was such a success that we have booked him for Feb.6 to come back to our school and perform to raise money, for a Family Night.
He has a web site if anyone is interested.
Currently we have 2 assembies coming up . . . The Portable Planetarium and a free assembly sponsored by McDonald's called "It's book time with Ronald McDonald". They offered several assemblies this one just fit with our curriculum best. In the past we have had our local Children's Museum (The Pacific Science Center based in Seattle) come and do presentations. We had Missoula Children's Theater come and work with a group of kids to put on a "mini play" for the student body. Next year we are planning on having a local wild bird sactuary come and do a presntation. Last year we had a Seattle Theater group-Fifth Avenue Theater-come and do a presentation as well as "The Reptile Man". I hope this helps.