Yes, both Semaphore and Buildkite offer a Free Trial.
Semaphore is designed for Individuals, Freelancers, Large Enterprises, Medium Business and Small Business.
Buildkite is designed for Large Enterprises, Medium Business and Small Business.
Pricing for Semaphore Starts at $20/Month whereas for Buildkite Starts at $2,999/User/Month.
Some top alternatives to Semaphore includes Clustered Cloud, Codeship, GitLab, CircleCI, Bamboo, AutoRABIT CI, Buildkite, Travis CI, Codefresh and CloudQA.
Some top alternatives to Buildkite includes Codeship, GitLab, CircleCI, Bamboo, AutoRABIT CI, CloudBees Core, Travis CI, AppVeyor and Drone.io.