I agree that once you're above a decent speed, it's hard to tell the difference. IMO, that speed is 10 to 20 Mbps. The only reason for more is multiple users sharing one connection while streaming/gaming.

$70 is not cheap. But IMO, you're getting a lot for it.

My connection is cellular. The usage cap is 15 GB per month and my speed varies from 3 mbps to 15 mbps. The cost is part of my shared data plan but as a separate purchase, it would likely be around $50 per month.