Rents have been skewing much higher than mortgage costs for some time. I'd guess it's 2-3 mo. of rent, max. In silicon valley it might be 1-2mo.

But people often don't think rationally that way (and definitely not all the time). A large lump sum may seem bigger than it actually is. Which is why sales folks often try to peanut butter the costs over a range ("it's the cost of one coffee a day for a month!")