Honest answer and reaction?
I don't reply. I simply block and keep it moving.
I can't remember being asked this exactly, but I get messages that imply they can't pay my rates. For example, I get the odd request for 30mins or 15mins after they had seen my minimum rate. It means they can't afford it, so asking me "how much is 15 mins?" is annoying lol.
Also, instead of getting messages about how expensive my rate is, I got them questioning my deposit requirements instead...
If they had contacted me on WhatsApp, I block them there and do the same on phone. That way I save them the trouble of ever contacting me again and myself the headache of dealing with such unwanted enquiries.
When I was starting out, I would have replied, but experience thought me I was doing too much unnecessary gymnastics and wasting energy on time wasters.