I counter offer with 380,000 USD (515,000 USD ARV) and i will be charging each unit 1,900 USD (1 percent rule) a month.

Unless he is very close to you he will probably charge more in interest than a bank so if you qualify for a traditional loan that would probably be more cost effective. 

Is there a way around it to get a conventional 30 year loan on a fixed rate for a 6plex?

Regarding valuations:  There's no strict convention. 

He's looking to finance MOST of the deal through conventional financing, but may need some extra cash options for a small amount. 

And the bank is charging me $670.00 AGAIN.

If the owner hasn't refinanced, I calculated that they'd likely still owe around $13000 on the loan if they had a 30 year mortgage and they made the regular payments each month.I started with the conventional financing route.

FYI if you plan use a site like Home Advisor, they charge each contractor a sizable fee (usually 4 companies) to get your info.

Just charge a pet deposit and monthly fee?

I would like to obtain financing on this property so I can use my original investment on a different property.I do not want to use conventional financing because it will take too long to close the loan and we anticipate the property to sell very quickly.