House needs new HVAC and gas line - need estimate?

[Lance Borden]

I'm evaluating a home that needs a new HVAC system (never had it) and a gas line (currently uses propane for stove, etc.). How much should I estimate that will cost, and are there any gotchas that should make me walk away from the house? It's priced about $20K under market value as a result of these needed repairs. If probably use it as a buy and hold and rent it out.