As a landlord in PA I highly agree. One - look at the listings that are there. BUT - also place your own ad. More details are good and work in your favor. Key words are "Single working professional, nonsmoker, one cat (fixed, no claws), great references, excellent credit etc (so long as it's all honest.
Be specific about areas you want. Ask for photos, addresses, map links, etc.
Landlords WILL find you, if you advertise to them!!!