What would be an estimated value to emulate 500 devices?

For Genymotion SaaS, 500 virtual devices at the unlimited plan rate would be about $89,500/month billed annually or $109,500/month on monthly billing. This is based on the listed price of $179/month per virtual device annually or $219/month monthly. Pricing SaaS Genymotion for Enterprises

If you mean 500 devices running at once on pay-as-you-go, the cost depends on how many minutes they run, at $0.06 per running device per minute. For a precise quote at that scale, the best-value option is the private offer for large volumes. Pricing SaaS Genymotion for Enterprises