[emb-fit]

Mentioned some of this in another comment:

"It's a $2k training bike. You could spend $1k and get a really nice brand new road bike and a smart trainer that controls resistance like a Wahoo Kickr Snap (or several others) for ~$500."

That being said the M3i seems to be one of the more flexible options if you are gonna go the stationary bike route.

[Johnny555]

$1K would get a decent road bike, but not really one I'd consider "really nice".

I have a really nice road bike, and a decent steel framed commute bike. I've used both on a trainer, but it's not the same feel as a spinning bike, particularly when standing up and cranking hard on the pedals.

A good spinning bike will last a decade or more with little maintenance, but you'll be changing tires often on the road bike trainer as well as all of the other maintenance that comes with a bicycle.

You can get a good workout on a bike+trainer and if that's all your budget (or space) allows, it's a good option, just don't expect it to be a spinning bike.