You can find yourself accomodation in one day (sheer luck); or may be it'd take over a month.

agents/ well, they work hard .. they do this worldwide and ofcourse they will take their commission. If you hire an agent who show you your desired aptt in your budget or area of choice, you should acknowledge he did hardwork and he saved your time, energy and efforts.

so, you can always avoid them if you have plenty of time and no rush;
but as their commission
15 day rent is normal, i think so.

however if rents are high above the sky
normally the landlord cover agents expenses.