Custom software is not cheaper because it is custom. It can reduce cost when you are paying for several products that each cover a slice of one process.
A typical pattern: CRM, quoting in a spreadsheet, a generic store, and email for everything in between. Each line looks small. Together they cost more than a system designed around the actual sales flow.
The other saving is time. If people copy customer details between systems, or rebuild reports by hand, that labour is a subscription you never notice on a card statement.
Custom work is a poor way to cut cost if the current tools already fit. In that case the spend belongs in training, cleanup, or a smaller integration — connecting what you have so information is entered once.
If the goal is fewer tools and a process that matches the business, look at business systems and integrations together. One replaces the awkward middle. The other stops the remaining products from living in isolation.