Is IT more focused on buying or building solutions?

There's a practical rule of thumb: cost of opportunity, the time needed for development vs. deploying an existing solution.
Also, the more core-business the less you're likely to find an external "tailored" solution, adaptations are to be expected for business practices and software.

In my current organization (very large state university system) there is a strong emphasis on buying off-the-shelf solutions, especially in our centralized IT division.  This makes sense because OTS software minimizes the burden of support on the purchasing organization.  It also pushes the responsibility of security and accessibility compliance onto the vendor.  However, OTS software still requires integration, and as such there remains a need to retain technical skills in the organization to ensure all the OTS software plays nicely with each other.

Additionally, many departments in my organization have very acute and specific needs that simply cannot be met by OTS software -- or if they can be met, the solutions provide so much extraneous functionality (at great cost) as to not be remotely feasible as a solution.  As a technical project manager in such a department, I manage a team of developers who build custom software solutions specifically to address such acute/specific needs.  We also integrate a lot of OTS software into our custom solutions.

In summary: central IT defers to buying solutions but many departments require small, niche-specific custom solutions to be built in-house.

Definitely buying, but we try to involve other groups or business areas to work with us proactively.  Of course, that's not always successful or as collaborative as I'd like.  We are a law firm, so getting people to spend time really discussing their needs can be a challenge. 

I think IT is often focused on buying solutions, as so many new solutions claim to solve all of your problems. I have always focused on a combination of sometimes buying sometimes building. I think people sometimes don't want to do the hard work of innovating to get the right balance of solutions to actually solve all of their problems.

Buying when to comes to operations all SAAS but for engineering in support of our offering, building but utilizing 3rd party solutions for all things monitoring etc.