Buyer arguments in favor of commoditization might sound something like this:
To these buyers, the fact that the widget might be half as strong or half as durable or twice as likely to stop "widgeting" when they really need it most is not more important than low price.
Viewing supplier companies side-by-side, to see which provides better wrap-around services and support, etc., often reveals a differential that clearly separates the product offerings. Value, then, must be mapped against this customer's needs and viewed from the perspective of the total ecosystem.
Now, if you look at the total relationship between your firm and your customer and it is, in fact, exactly the same as your competitor's relationship, then you don't have a negotiation problem, you have a non-existent value proposition.
The bottom line? Expect buyers to attempt to commoditize; it's what they're paid to do. And it's the job of the B2B street fighter to combat commoditization at all costs. You must be able to articulate value; it's the only thing that will take the pressure off of price and keep the deal from being reduced to a price war over a commodity product or service.