Proof of funds for apartment purchases?

[John Story]

Is it typical for the seller or his agent to require proof of funds just to look at the property. I have came across this several times recently.  I'm looking at 12 to 40 unit properties.  I will raise private capital for the purchase.  I do have other properties but they are leveraged to some degree.  Not a ton of useable equity there.  Any advice is much appreciated.

Thanks