The software is nearly free at small scale: mainstream platforms run $0–$50/month under a few thousand contacts, scaling with list size. A solo service business rarely needs to spend more than $30/month on the tooling.
The real costs are elsewhere: the time to write (or the $200–$500/month a freelancer charges to write for you), list-building assets like a good lead magnet, and, for cold outreach specifically, separate domains and inboxes (roughly $3/inbox/month plus ~$11/domain/year, per our infrastructure planner).
Which is why email's famous ROI holds even after honest accounting: the marginal cost of re-contacting people who already know you rounds to zero, and one attributed job a quarter typically pays for the entire program.