JSCOTT said "perhaps ask the seller upfront if they will pay a commission before you speak with an agent" This approach/FSBO agreement/ is highly unlikely. What would you do --run around and look for an agent after the fact, or hope you can get an agent to agree to write a contract for you at a reduced commission. Also, if you already have an agent it would be counter productive to approach a seller directly.
The reason a FSBO is selling under most circumstances himself, is because they do NOT want to pay a commission. Many FSBO sellers do not understand the complexities of the Realtors job and getting the property closed. Agents work hard to earn their commission.
Best to let your agent contact and work out the commission with the FSBO -PRIOR to you showing up. This is a good way to entice the seller with YOU --the buyer. Exclusive agency agreement can be signed between FSBO and your agent. Then, to move forward your agent has agreed to a reduced commission or a transaction fee to assist in follow thru and closing.
The good news is, if none of this works out, most sellers eventually list their properties with a Realtor, and at that time you could make an offer on the property.