If not, upgrading existing databases or converting from one or more legacy systems will be your lot. Make sure that you fully understand what systems will still be in place after the migration and how they will be integrated into your intranet. With a more moderate budget, you can replace inefficient systems with newer and more powerful ones. Remember that computer hardware, memory, and disk space are cheap. It's the software and operations that are expensive.
Powerful hardware can make even today's bloated software work faster.
With a higher budget, consider migrating legacy databases to a single powerful commercial database. Their fee will be well worth it. Performing a requirements analysis is critical to the success of any project. Without a clear goal in mind, success is dubious. Identify all data sources and formats.