Just some thoughts to keep in mind when you are looking at commission. It IS negotiable. The customary rate is 6% (which means the brokerage fee is split 50/50 between the listing agent and the selling agent, equaling 3% to each side). Specifically the 3/1.5 means that the commission structure is 6% on the first $100,000 of sale price and 3% on anything over and above $100,000 ---- hence the 3 and 1.5, because it is split between the listing and selling agent. The other common commission structure is 7% - which equates to 3.5/1.75.
Remember, as a buyer who is looking at listed properties with a licensed agent---sellers who have signed listing agreements and whose properties are listed on the NWMLS have agreed to pay the brokerage fee. The agent that you work with is representing you, although they are paid by the seller upon a successful closing, according to the terms of the listing agreement.
Hope this helps and Happy House Hunting!