Sales is a tough job, you win or you lose, with no middle option. Understanding those you lost is the key to improving future performance.
Over 30 years of engageing with sales people, managing sales forces, and doing sales training, it seems to me there are just 5 reasons that seem to be recurrent in a failed B2B sale.
- Failure to understand that a potential customer in not interested in what your product can do, or has done, just what it may do for them. Trying to sell the features of a product, rather than the benefit it delivers, tailored to the circumstances of the buyer is sales death.
- The power of incumbency is huge, vastly underrated in most cases. When getting a sale means someone else is missing out, the risks to an organisation, and the reputation of the one who makes the change can be significant, so failure to remove the risk usually leads to failure. The old adage “nobody ever got fired for buying IBM” still holds.
- Failure to communicate and convince the decision-maker. I have seen huge efforts go into making sales, and as the effort drifts, it becomes apparent that the one who makes the decision, the Yes/No person, is not engaged, and often not even known.
- Lack of up front resources, or content that serves as an alternative to the traditional sales effort. In this day of the net being used as a primary information source, it is often the case the specifications of a purchase have been determined, and a purchase decision made, before a potential supplier is aware of the process. The processes of qualifying a lead, supplying information that contributes to a specification, building relationships, and determining price and delivery requirements, previously the function of sales has moved on line, the only variable left is the “who will supply” question.
- Price. This is almost always the reason that gets cited as the one that broke the deal, but usually it is just a convenient excuse when any of the other four above have kicked in, and the explanations just get too complicated. It is the “Dear John” of the purchasing officer.
StrategyAudit 
I don’t think price should ever be used as an excuse for not making a sale. Now more than ever there is so much added value that sales people can give that price (unless the product is priced way off in the market…) doesn’t matter to the average consumer / buyer.
I agree, but some markets are harder than others. For example, the retail supermarkets have taken then marketing initiative with housebrands, and are stretching the capabilities of proprietary brands, and as retailers control their shelf space allocations, are in a dominating position. In B2B, there is far more opportunity, and the net has on one hand democratised product availability, on the other hand made price transparent, so the creation of value has to be both more sophisticated, and more transparent than just a few years ago.