Surprised no one here is saying Washington state…
No you cannot afford Seattle metro areas but you might be able afford within ~2 hours of Seattle. I’d look into Northern WA state near the CAN border – you can be at Thunderbird in a hour or less and to Seattle in about 1.5 - 2 hours with light traffic.
Also no state income tax.
https://www.horseproperties.net/properties/whatcom-county-washington-united-states
Oh shit I see your $600k ask for a farm property … you might find a SFH in WA for that in Whatcom – but yeah if you’re looking for a horse property with house and existing infrastructure for that price I’m gonna say rural south / midwest, or NY state / NH or Vermont maybe?