The picture is the first herpstat and I would suggest that is far too much for one. The new equivalent is herpstat basic, new is 115$. The price on the intro is 9$ less than list that too is too much for used IMO. The helix is also 20$ under list. Too much for used IMO. The last used stat I bought was a herpstat pro with three probes (one was lost) for $185CAD (in Canada and no shipping) when the new replacement is $339USD.
For an incubator I would suggest herpstat intro+ for 109$. The safety relay will shut down the power in the event of a massive failure it is like having a fail safe built in. That or a herpstat 1 (not the 1 basic) as it can be used for other things when not doing incubation (like controlling a humidifier or lighting) It is only $139