If you have a quarry close to home check on the cost of "screenings", around here they sell that stuff for like $2.40-$2.50 a ton plus trucking, cheaper than sand around here, and IMO the screenings work better, while they will still wash out, it stays put better than sand.
Most places will fill a pickup bed full of sand or screenings for around $25.00, which should be plenty for your pool size.
Most places will fill a pickup bed full of sand or screenings for around $25.00, which should be plenty for your pool size.