You can get Pemrithrium in Ortho 'total kill' insecticide at Home Depot, $8.00 and change for a quart of 2.5% solution. Take a spray bottle marked and dillute it 4:1 w/ water to make the 0.5% solution like the spray cans. For less than two cans of Repel you get enough to last a few years.
A nice tip. The cans add up with both of us using it.
Guy
and does kill ticks. Check the info sheet at the link, but you have to be careful how you use it as it is toxic to bees, fish and other critters. Today looks like an excellent day for tick collecting 