I've never used a realtor. I have called realtors and asked if they knew of any rentals in the area I was seeking.
I have also found that renting directly from an owner is usually better. They don't seem to charge as much for their property, and are easier going about changing situations. Whenever we've dealt with a company, we've found them super strict about what we can do, and we didn't get as much of our deposit back. Direct owners seem to care more about their property.....although not always the case.
When looking on CL, be aware that one of the scams is that someone will copy a legitimate ad, and then lower the amount. Then when you contact them via email, they send you a message saying that they are out of the state/country etc., and are using a realtor. They want you to fill out an application via email or online. They are fishing for information, and deposit money. I suggest opening a new email address to use when corresponding to CL ads. If you get someone suggesting any of the above and do not give a contact number, skip it. I also go through all the other ads on CL (even out of my price range) to see if I can find the orginal ad. We came across this exact scam in MN and in IN. We found out by actually going out to one of the houses to look at (not scheduled), and found the actual owner there. He lived next door. I told him about the ad I found, and the response I got (about owner living in another country). He actually had me forward my email to him so he could report it. And the price difference was about $300, and it was already rented.
Good luck! Just remember, if it's too good to be true, it probably is.