My transceiver has a built-in wattmeter but I've decided to buy an outboard one to monitor the antenna system before it reaches the ATU. I'm capable of putting out 100 Watts and I see that several manufacturers offer meters in the $50 range that look to be adequate for my purpose.

On the other hand, I see that there are a lot of hams who have opted to spend around 500 - 750 bucks for a portable, lab-grade wattmeter. Is it really that critical to get another 3% - 5% accuracy to be worth the additional cost? Obviously, there are many who believe so. What am I missing to see here? Would I be wasting my money to buy a cheap meter?