I made screens with glue gun and strip magnets. They worked great until we traveled to hot climate areas and then the glue melted and released. I ended up using a regular adhesive (tube) glue that worked better. I sold that van and the screens went to the new owner and I purchased skeeterbeaters for the new van. They stitch regular round magnets into folded over screen material. Looks more finished, no glue melting and easier to store as they fold up nicely. I would recommend either purchasing or making your own in a similar manner.
Oh and glue guns are cheap; you can find for $5-10 at Lowes, Home Depot, Harbour Freight and Canadian Tire if you want to go that route. Don't sweat over another tool that you can always find lots of little projects to use it on. I actually have 2 of them (lost one for a while) so went out and purchased another one for some other project that needed a glue gun.