The parents and students in your school simply cannot afford to pay for this. That's something the mom's on here aren't taking into consideration.
This is a LOW INCOME SCHOOL which means that a lot of these families are on welfare or disability or working for minimum wages and struggling to just pay their own bills.
Fundraisers that solicit at the school won't work. They have no money.
Can I suggest you consider some things we've done in the community in the past that were successful.
1. We got free spots on the radio and in the newspaper and asked for donations for garage sale items for a couple of weeks. We had a local car dealer let us use one of his back buildings to store it all in until the sale. Teachers and parents gathered the items as we got calls for donations. We had volunteers get together a few days before the sale and we priced everything with stickers. The prices were reasonable so everyone that can could find something.
We advertised on those same radio stations and the paper did a story on the fundraiser so that was free publicity too. Since it's for a school and not for profit the radio stations should give the ads for it freely.
We raised over $1200 in that one sale alone. The community came out like crazy. We covered the back parking lot of the dealership too. It was a huge success. All leftover items went to a local thrift store that had good prices and worked to have affordable items for those who shopped there.
2. Go to gofundme.com and do one. Then have every single parent share it on FB, tell them to have their friends share it too. I did one last year and I raised my goal in less than 12 hours. It was extended family that donated but still, this need was met. In my goal I included gasoline, the cost of the event, food allowance, and a keepsake item. They do keep a small portion of the income so you need to make sure the goal will completely cover it.
If it's not shared over and over and over it won't do well. Even if a family can only donate a dollar they should know that will help. Make the goal more than you need. Just to cover their lunches or something extra.
There are several other sites that do this sort of thing. They contacted me after I did mine and told me they would have charged me less or even nothing. I hadn't heard of any of them.
3. There is a site where schools can go to apply for grants for particular activities. Call your admin office and find out if they know of any that are in your area. Getting a grant can be time consuming but it's free money and even a portion of the goal would help.
4. Have the kids sign up to go work the doors at Walmart for donations. All they have to do is be non-profit and Walmart lets them have time. We did both doors every year for BMX. BMX supports the Leukemia/lymphoma society and has a yearly fund raiser for them. We took the kids in full BMX gear and they would go up to the shoppers coming out and ask them if they'd like to make a donation to the Leukemia/Lymphoma society to help them find cures.
We had people giving $5s, $10s, and $20s. Of course they were donating to a well known charity and felt safe the money would be helping vast amounts of people. I would think even if shoppers donated a dollar each you'd get a bunch of money.
Do this on the 1st or the 1st Saturday of the month. This way you'll get all the people in town that only get paid once per month. If those Saturdays are all taken then do this on the Saturday close to the 15th for those who get paid twice per month.
5. Can you have parents volunteer to stand in intersections to collect donations from people stopped at the light? I know our fire department does this a couple of times per year to raise money for items. They use their firemans boots to hold up for money.
6. Do a door to door sales thing. I know, I hate them too but if you target neighborhoods outside of your school they might be able to sell candy bars at the parents jobs, church friends, club friends, etc....
Those are some that we've done that were successful, well, I have never stood in an intersection with a fireman's boot but I have put money in that boot.
I think you need to think outside the box on this one. I've helped raise thousands of dollars and it takes planning and volunteers. I hope you can find something that works for your kiddos.