CPAP's will most likely always be "perscription" only. While they are great for therapy of OSA sufferers, a CPAP system that is set incorrectly can cause problems.
This is why sleep studys with titration are needed, so that the correct pressure is provided.
At best, I would see Auto-CPAPs as the only devices that may someday more widely available without a prior sleep study, as they auto-titrate and self select the best pressure for that specific patient.