Amazon has the NERF Fortnite HC-E Super Soaker Water Blaster for $9.99 - $2.50 off coupon (check "Apply Coupon") = $7.49 with free shipping on $25+ or with Prime. Target has it for the same price after 25% off Target Circle coupon (click "Save offer"; Exp 3/13), however there is no pickup available.

All this water play stuff is hard to find right now.