Your question is a bit unclear but my sense is that you want to know if the school district is responsible for assuring that children with special needs are able to participate in an overnight field trip experience which may involve costs that the child's parents may not be able to afford. Basically the rules are if the activity is designed for all children to participate then the district has an obligation to provide appropriate accommodations. While you do not specifically identify an issue, I am going to propose this example: child is mainstreamed with an aide during regular school hours. In order to participate in the overnight field trip the child will need both an aide to assist with education related issues but also an aide to assist with personal care, i.e. toileting, bathing and dressing. If this is the case, my first position is that the school district is responsible for providing an aide to assist with the educational matters as if the child were in a regular classroom. Other resources may be needed to address the non-academic issues and the school district may be one of several resources that should be available to support the child. Options may include having a parent or family member accompany the child and be responsible for the personal care issues. If the child receiving In-Home Supportive Services, these resources may be available to pay for the caretaking that needs to be done during the overnight fieldtrip. This may be more hours than the child normally uses so the county welfare department IHSS program may need to be asked to provide additional hours to cover this expense. If the child is a client with the Regional Center that serves the area where the child lives, this may also be a resource for providing for the costs of an aide for the trip.
I recommend that you contact Disability Rights California and the Special Education program in your district for specific detailed explanations of the responsibilities in this matter.
On behalf of your students I would like to thank you for being proactive about this issue and wanting to make certain that all of your students are allowed to participate in the overnight activity.
This is not a substitute for a consultation with an attorney with a background in educational rights for students with disabilities.
Are you a special ed teacher? This is potentially the result of a lack of understanding of the law. If the trip is made available to other students without charge as part of the educational program, it must be made available without charge to special ed students. If there is a fee for the trip, then the fee should not be different for special education students.