Symptoms
How to create a workflow that, based on a data field, will either kick off one sub-process vs another sub-process.
Diagnoses
Possible with conditional outcomes and the 'Call Sub Workflow' event.
Resolution
Define two outcomes off an event in the workflow, edit them, click 'Add Context Statement' and create conditions based on your cost amount data field. When the workflow arrives at said outcomes it will chose one path to go down based on the result of the conditions. Add 'Call Sub Workflow' events to the empty events at the end of those workflows, specifying which workflows you would like to launch.