I'm a consultant. I work for a pretty established consulting firm. That's my perspective. Recently though, I've been getting some real world experience on how tough it must be for a company or individual to hire a consulting company to work with.
You see, I am in the midst of remodeling my kitchen. It's now time to purchase cabinets and the process has been extremely challenging. I've noticed some parallels in that industry that mimic mine and its helping me understand the process a bit more. Mind you, it is not helping me make the decision, just helping me understand why I am struggling with it so much.
For starters, the solutions are complicated. With a ton of options out there and many different configurations, putting them all together is difficult. Whether it's software or cabinetry, you really need someone who has practical experience using and implementing the different components. Like everything out there, you can do your due diligence on the Internet and research the pros and cons of various things but without real world experience, it's tough to accurately cut through to the truth of a solution.
Designs are presales activities but they are not free. This is a delicate balancing act that is walked by the vendor. You, as the client, want and need to see as much detail before committing to a project and the vendor needs to provide enough for a client to be comfortable but not so much that they just go out and purchase it themselves. Or worse, that they they just bring it to a competitor to price out. The design component is part of the value add that the firm brings to the table. I can understand and empathize with the protective nature of this process since a vendor doesn't want to see their ideas implemented by others who undercut them on cost and leveraged their presales design experience.
Budgets are just estimates and starting points many times. Since you are working with very complex solutions with seemingly unlimited options and variables, it is very difficult to get a precise true cost. As the customer, you most likely don't even know all the options until you begin to get into the post sales design work. The potential lack of exact details in a presales design also contribute to the lack of financial accuracy. You can get a range that should be close but it really won't be vetted until you start the engagement and are committed to the vendor. Any number of things can drive costs up or down once you are in the thick of a project.
Choosing a partner is an exercise of trust. You can meet and interview tons of people and definitely get a feel for who you jive with and who is competent but that doesn't necessarily guarantee the best outcome. It also becomes increasingly hard to fairly compare solution providers apples to apples as the complexity of a solution increases. You can get referrals, view past work and scour the Internet for praise or belly aches but at the end of the day, you are probably just trusting your gut.