How far is too far when looking for rental properties?

[Christian Pietrantonio]

I'm looking to invest in rental income properties but due to the fact that multi-family properties where I live are expensive, I would need to go further out to find better deals. 

How far is too far,1 hour away or 2 hours away? 

Whats a general rule of thumb when it comes to buying properties bit further out from where you live? 

Thank you!