To find if they are motivated quickly on the phone I like this tip I was given recently-
Ask them "Why do you need to sell, is it because something major is wrong with the house?" Or, "Just curious why you are selling? & I ask that because I had someone once try to sell me a house with a (Insert: "A title issue" OR "because the foundation was sliding into a lake")
A lot of times this will get them to offer their true motivation instantly. If they are motivated they will want you to buy it.... and if they want you to buy it they will attempt to ease your concerns that there is a major hidden issue by blurting out the motivation.... "Oh no, nothing like that, it needs some work but my wife left me last year and it's been tough"
As to the original question, you need a license to collect a fee, but getting your license solely to collect a fee isn't that expensive (No MLS or Realtor $$) but you can say "hey Mr. Unmotivated Seller, it sounds like something I might not be interested in, but I have access to the MLS & can find out who the agent is that has sold the most amount of homes near you over the last year and put you in touch with them if you like.... The only thing I ask is that for me doing that for you, you have to promise to keep me in mind if one of your neighbors, or someone you know, has a house they need to sell quickly"