Buying Subject to Municipal (CV) Liens and Negotiating Them Down

[Devin Beverage]

Boy, has it been a while since I've posted on BP! I'm still here in the Tampa - St. pete market, constantly on the hunt for good deals.... :-) 

I'm looking for feedback regarding buying property with Code Violation liens in place from the city, for things like mowing the grass, clearing debris, demolishing a dilapidated and abandoned structure. This is in regards to a specific deal, so for the sake of context: 

• The property is Vacant Land, originally had a house that the city demolished due to abandonment by owner. 
• Back-taxes of ~$2650 (headed toward tax deed auction, but perhaps not for another month or so because there is no set date yet)
• Total Liens add up to ~$6,000, without any interest the city may have added since they have been unpaid for a few years - I'm still waiting to hear back on that, but I don't think they were interest bearing liens. 

The seller is willing to walk away with $1,000 net, and I'm pretty confident I can sell the lot for ~$30,000 -- So it's a pretty solid deal so far. Now, for the part I am NOT as sure about:

My question is, can I maximize my profit by buying subject to the liens and negotiating them down or potentially having them wiped out? 

I've heard from about a dozen or more seasoned investors about municipal liens being negotiable - my question is, how? I'm going to sell this lot to someone who will build on it, so I can't promise the city that I will build on it, though maybe I could say that a new house WILL be built on it. The bottom line is that I lack the knowledge of how one goes about cutting down on the actual amounts the City wants - no one ever goes into detail about the execution. 

What has been your experience?