Plan on spending a LOT of time learning about those machines before you buy.
Make sure you try a Octane. I am not expert on the things, but I did consider buying one.
I liked the Octane the best, but it was close to 3 grand.

I wound up getting a Concept 2 rower. It is superb. I'd suggest getting
one used (and only that brand) but try to get one with a PM3 or PM4
'computer'. Mine is an older model, doesn't have the games, and trust me, they
help a lot.