It will not spray with a cheap plastic sprayer. The thickness and the solvent will ruin a plastic sprayer.
On another note, it seems that your sand is too high. It should be done a 1/4 to 1/2 lower than the top of the paver. This would stop the sand from being removed when applying with a roller. In addition, use a sponge type roller. They will have less of a chance of getting down in the sand joints.