Buying agents do next to nothing for their 3%. Every listing is online and you know better than then do as to what you want. I've gone through the last 2 house purchases using this model:

1) Find house I'm interested in.

2) Contact seller's agent to look at house.

3) Look at house.

4) If I like house, tell selling agent I will use them as a buyer's agent if they cut me a deal on the commission. (Normally they would split the ~6% between the buying/selling agent but in this way they get 4-5%).

5) This also puts my offer to the top of the list for the seller's agent as they now get a (much) bigger commission.

6) Hop the line, get an accepted offer and save 1-2% of the purchase price.. heck, this last house I even lowballed versus another offer and their (greedy) realtor encouraged them to take my offer over another higher one. On a $675K house I saved 1.7% on commission and saved $5K versus another offer they received.

tl;dr: Buyer's agents do the literal nothing and realtors are greedy bastards.