What will it be powering?
There's Deepcool PM650D, an 80+ gold PSU for 5k.
RM650 will be a top tier PSU in terms of quality. Top tier PSUs are highly recommended for higher end systems, like sometimes momentarily the system power draw might spike too much, tier A PSUs will handle those better & so on. Basically if you are spending 120k+ on components, you can spend 9k for a good PSU to go with it.
I feel RM650 & RM750 are overpriced here. I bought NZXT C750 for under 9k, another tier A PSU. MSI A750GF & A650GF are tier A as well.
Also modular vs non-modular adds cost depends on you if you want the former, but almost all top tier PSUs are modular.
A good deal at 7.8k:
Msi MPG A850GF SMPS - 850 Watt 80 Plus Gold Certification Fully Modular PSU With Active PFC
PSU only draws how much is required from the wall.