Can I buy a home that isn't for sale?

You Bet.

You should be able to go directly to the Homeowner, assuming they're not still represented by a Real Estate Agent. If you find out they have representation then you should contact the Listing Agent. And in most cases you may end up contacting the Listing Agent any way, which is fine since the commission is always paid by the seller. In other words, you 're really not gaining much of an advantage when you go directly to the homeowner.

I'll give you my real life example...Before I contacted anyone I first did a Market Analysis of the home my client was interested in and found the value decreased since the home was originally listed. I then called my client and gave him my recommendation on price and went ahead and contacted the most recent Listing Agent to find out if the homeowners were interested in selling. Unfortunately the homeowners were NOT interested in selling and were happy with the renters they had. Instead I showed my client some other homes that fit his criteria and went from there.

This has nothing to do with my experience...However, if you find the Listing Agent isn't helpful or friendly or is just a jerk you now know why the home never sold. Aside from contacting the Listing Agent you can also talk to the renters and neighbors to see if they know who the owners are and how to get a hold of them. Once you have the homeowners contact information try email, phone, Facebook and/or a mail a letter. If you really do want the home you should try every avenue you can.

I've contacted homeowners and landlords in the past that have held on to a letter I sent over a year ago before contacting me and letting me know they were interested in selling and wanted to know what I or a buyer I was working with was interested in offering.

It never hurts to try. You only miss out if you sit on the sidelines.