Amazon has the 4-Pack Pelican AirTag Holder Case w/ 3M Adhesive Sticker (Assorted colors) on sale for $24.60 with free shipping on $25+ or with Prime. Can be used to stick AirTags underneath a bike seat, within luggage, inside a car, etc. Less than $7 per case.

• Alternatively, there's a Cityway 4-pack option for $14 after coupon. (mostly free product Vine reviews though)