Heart Rate Monitors and Fitbits (recommendations?)

I can recommend the Garmin Forerunner 35 which should be within your budget.
It offers plenty of useful functions including HR monitoring, satellite tracking and different profiles for walking/running/cycling/cardio which means it does a better than average job of keeping track of your daily calorie burning.
It's also fully waterproof, has a screen you can read in direct sunlight and looks really good. It can sync with your smartphone using the Garmin app and/or talk directly with your computer via USB, so keeping your data updated is easy.
I've found the HR measurement to be as good as chest straps but without the added hassle of wearing an extra monitor and having to sync readings.

I have a FitBit Charge 2 and find it to be very accurate. I lose weight exactly as predicted based on the calorie burn it reports.

I do almost no "steady state cardio" but I walk a lot (average 19,000 steps/day). I get very few "bonus steps" (in other words, "steps" from moving just my arms). I do a circuit-style workout class twice a week (for a total of 2 hours/week), and the calorie burn FitBit suggests for that seems pretty reasonable (~400 cals/hour including BRM) but it's a tiny fraction of my weekly calories so if it's off by 100 either way, I wouldn't notice.

For someone like me (on their feet a lot; minimal gym-based exercise), it's a perfect choice. And it's purple!