Are they arbitrarily increasing prices since they know you are keen to book?
You can test it yourself by changing IP and using some incognito browser (or just changing device).
It sounds to me like some price that was available in the past and then was not anymore (but it could reappear in the future). As Kate commented, they probably default to "someone booked it!" to try to rush you into buying something. Agoda is full of nasty tricks to rush their customers to buy some accomodationaccommodation: time pressure, fake discounts, etc. While Agoda is legit (they do book hotels at the agreed price, which of course only appears at the last page of the booking, and hotel descriptions typically match the reality), you can't trust anything they say about price, time and availabilities.
SomeFYI, Can hotel booking companies make up any "original price" they want, or does the claimed original price have to be somehow grounded in reality? and here are some of the many other examples showing agodaAgoda tricking customers: