Rent in High Value Neighborhood

[Ben Le Fort]

Hi, 

Thinking of buying a new house and renting out my current house within the next few years. The neighborhood has really shot up in value over the past few years and houses are selling for $500k+.  

My question is there a formula you use to determine rent in high-value areas (maybe 0.5% of value?) or should I really only be going off-market/rent reports for my area? 

Thanks,

Ben