I've used the Hm digital TDS4 pen before with good results. Adjusting is simple too with a solution whose TDS you know, and a small screwdriver. Also nice is that this model comes with a water temp sensor.
As for ph, i always used the dripper in a vial before, but for this round i ordered a digital meter. I actualy lost my old TDS so ordered an hm TDS3 and hannah checker1 ph meter from sunstoneherbals.com for $50 shipped, a slight savings. the tds4 can be had for a few more dollars but i already have a temp sensor for that. Havn't found many bad reviews of the cheap ph pens, just that they need normal recalibration. For something i use once a day i dont figure a once a month calibration is too bad.
I also ordered a little .9999 silver wire from them. Saw a post here before about making feminized seeds with coloidal silver(easier than it sounds), and figured having a little arround if i want to try would be nice. I've no clue if their silver price is fair though, just that the meters were cheap