It is important to think about the ideal hardware set-up when deploying Intermapper for an industrial-strength enterprise deployment—when you wish to monitor 200 or more devices, for example. With the database enabled, the key factor becomes the number of datasets that you're exporting. By default, that includes response time and short-term packet loss for all devices, plus sent/received bytes/sec for all interfaces. If each of your devices has 16 interfaces, that would be 2,000 * 2 + 2,000 * 16 * 2, for a total of 68,000 datasets.
Ideally, the best set up for someone on a budget would be three machines with the cheapest consumer-grade Core i7s and 4/8/8 GB of RAM for the IM, IMDC, and Flows machines, respectively. If you were still under budget, you could obtain an SSD for the IM machine and SATA RAID0 for the IMDC & Flows machines, with some money set aside to cover the fact that SSDs and consumer SATA drives tend to fail a lot faster than server-grade SAS.