What to build, and what to buy
Most teams do not have a software shortage. They have a fit problem. The useful question is which work is common, and which work is yours.
Buying is the right call when the work is common and a product already does it well. Accounts, email, payroll, a straightforward website: the cost of building those yourself is rarely the interesting part. The cost of maintaining a private version of something the market already looks after is.
Building is the right call when the work is how you operate. The gaps in a product, the spreadsheets around it, and the hours spent bending a team to fit a screen are the bill you are already paying. A custom system earns its place when it removes that bill, not when it is newer.
A consultancy should be willing to talk you out of a build
If the honest answer is a product you can buy this quarter, that is the advice. A partner who only gets paid to build will find a build. We would rather be the people who help you choose, and then deliver the part that is actually yours.
Start with one workflow that is slow, error-prone, or trapped in a tool the team works around. Describe it without naming software. If a product matches that description, trial it. If it does not, that is the candidate for something custom.