Proof of Funds . . . Strictly Cash? How much to show?

[Steve French]

This journey is never boring.  Once you've figured out an immediate problem, you get a little further on and discover another one you didn't anticipate.

This is one of those times :)

So we've got some cash, and some HELOC money, though more HELOC than straight cash at the moment.

I have read around the forums that a 'buffer' value beyond the asking price is what sellers really want to see in SOME account.  

For the ATL market, especially things near downtown in developing areas, as a cash sale, should I have asking price plus some percentage beyond that to demonstrate proof of funds?

For proof of funds, is it basically a checking account balance? I'm asking because it would, of course, be cheaper to keep that HELOC money IN the HELOC until we are sure we're going to make a (likely all cash) purchase. Likely we'll be doing some flipping or BRRR so keeping in the HELOC until the day it's needed keeps the holding costs of the money down.

Here's an example:

If I wanted to buy a dollhouse that costs $0.50, and I have $0.40 in a cash account, several dollars in a 401k, and a few dollars in a HELOC, could I show the HELOC or 401 as proof of funds? Should I show $0.50 available? Or would $0.75 look better? $1.00?