I also have an Apera PH 60 and like it a lot. Ive only had it 6 months or so but it has not need calibration yet, and I use it almost every day. Replacement probes are reasonable at $35. Plus, you can get an ORP probe if you want.
I had the cheaper PH 20 without a replaceable probe, and it lasted 18 months before needing replacement. This should work out to be cheaper over time.
My only complaint is it takes quite a while to finish adjusting to temp changes. I keep my rez in the 45-55F range, and it takes a good 2 or 3 minutes for the meter to read the correct temp when its starting out at 68F or so. All during that time, the PH reading will be climbing.