Worth Negotiating over $10K??

[Tim Kaminski]

Offering on a duplex that has been sitting for almost a month.  I have been looking for a few months.  I believe both units can rent out at $900-1,000 each.  Realtor said that the listing agent has had no offers and no serious inquiries.

Asking Price:$149K
Offer: $130K
Seller Counter: $145K
My Counter: $135K
Seller Counter: $145K "Firm"

I don't want to give in and pay more BUT I'm also really wanting to get a deal and don't want to lose it over a $10K difference.
Any tips?  Just suck it up and get it at $145K or stay firm and let them think about it?