Just taking the accuracy spec at face value, you're basically spot on, maybe good enough for a 2,000 count DMM. Anything higher and your last digit on the DMM will not be valid.
The $90USD LB01/LB02 published specs are 0.025%+1 digit (although only 24mA).
So $350 seems a little steep by comparison, but real world performance is unknown.
One issue is that test equipment can frequently be far better or worse than the specs. For popular products, you can get an idea of what to expect from other forum users.
From mostly a practical perspective, I'd suggest buying a decent bench DMM that you can get calibrated regularly instead. Generating stable voltages and currents is actually very trivial in my opinion, but you need an accurate DMM to go with along with that.