I personally use api test kits for my alk, ca and ph but for my nitrate and phosphate I am using Instant Ocean test kits.
Instant Ocean kits are very accurate and are highly recommended.
I picked up 2 nitrate and phosphate kits on ebay for $28.50 shipped
using test kits for dosing isnt always perfect , but buying an actual monitor will be super accurate but pricey, I wish I had the cash for a nice controller
The RKL basic package is fairly inexpensive and lets you monitor and control with the ability to expand with you get more funds
http://www.digitalaquatics.com/saltwater/RKL
Some of our Sponsors can get it for you too. I think Robert t Neptune (maybe the closest to you?) at one time could get it.