This discussion seems to be about two different aspects of a transaction:
1. A real estate agent will help you find, research, and negotiate the purchase of, a property.
2. An attorney or title agent will handle the closing of the transaction, collection of taxes and fees, and disbursement of funds, regardless of whether you use a realtor or not.
Since you've already found the property, you don't need help with the finding part. So the question becomes: How are your research and negotiation skills?
I'm a firm believer that a great real estate agent will usually more than pay for the cost of their commission by providing you with market knowledge, data to inform your negotiating position and offer terms, negotiating a better purchase price/terms, and often, advising you which deals you should walk away from. (Granted, I'm biased because I'm a licensed agent myself, in addition to being an active real estate investor and property manager).
Note that I said a "great" real estate agent. I'll be the first to admit that (just like any other profession), not all realtors are great, especially when it comes to analyzing investment properties and understanding investors' needs.
But, I assure you, once you find a great agent, you'll never even think about going it alone again...there's just no reason to.
On a related note, I hear all the time (and see posted above), "Just work with the listing agent...that way the seller will save on commission and you can negotiate a better price". This is not always true. The seller has already agreed to pay the listing agent's commission (often 6%) when they signed their listing agreement.
So guess what: If there is no cooperating brokerage (i.e. buyer's agent), sometimes they just keep it all*, rather than splitting it up with the buyer's agent!
This financial incentive, combined with the fact that the listing agent is contractually, legally, and ethically bound to represent the interests of the seller and get them the highest price possible for their property, gives them very little incentive to get you a better deal and save you money as an unrepresented buyer!
It's kid of like getting sued and then saying, "Nah, I'm not going to hire an attorney...I'll just let the plaintiff's attorney handle my case, that way the other party will save on attorney's fees and settle for less".
*There are certainly exceptions to this rule - An agent can legally and ethically can handle both sides of the deal in most states with a limited form of representation (typically called a transaction broker, as opposed to a single agent for the buyer or seller), or by continuing to represent the seller and having no agency relationship with the buyer.
And in some cases, a listing agent will have a variable commission structure, where they agree to one commission rate if the buyer is represented (6% for example, 3% for each side), and a different commission structure (5%, for example) if they find the buyer themselves - creating a win-win scenario (seller pays less, listing agent earns more). As a buyer, this tends work out if you're already working with a buyer's agent, and he/she happens to have a listing you're interested in.
The moral of this story being: Be an informed buyer, understand the different types of agency relationships, and understand what relationship the agent has with you and the seller. Never assume they are looking out for you (as the buyer) if they are the listing agent, and don't just assume negotiating without a buyer's agent will automatically save you money.