Get a liquid test kit like the API freshwater master kit. Hundreds of tests for what you need to know for about the same price as 5-in-1 strips plus ammonia strips (which only give you 25 typically).
There are electronic tests for at least some factors, however, the cost is extremely high. Checking google I could turn up one for pH for as low as $50 US, and one for ammonia for around $175, but that's only gaseous ammonia and useless on an aquarium. For the pH meter you'll also need a $16 kit with 10 calibration solutions, not sure how often it needs to be calibrated, but it sounds like something that'll have to be done regularly at least.
