Protesters say they feel let down after another bid to prevent more than 1,000 homes being built on countryside near Botley failed.
Botley Parish Action Group (BPAG) and the Botley Park Golfers had launched a joint appeal in the High Court against a decision to allow 1,400 homes to be built on land at Boorley Green, near Botley.
But a top judge has ruled in favour of the council that granted it.
And now campaigners must pay £5,000 of council costs awarded against them on top of their own £25,000 expenses.
Protesters said they felt let down and betrayed by Eastleigh Borough Council.
But BPAG revealed it is seeking urgent legal advice on whether there are grounds for an appeal.
This was campaigners’ second appeal for a judicial review of Eastleigh Borough councillors’ decision.
BPAG chairman Sue Grinham said the self-funded pressure group was “extremely disappointed”, but the court could only consider matters of law.
Campaigners had argued Eastleigh Borough Council had failed to ensure a five-year supply of land for development and to ensure it had a current Local Plan in place in time.
They felt it was unfair that the council was justifying its decision through these “failures”.
They also argued the council had breached European law on environmental impact assessment and that other sites are more sustainable. Campaigners wanted the development tested as part of public examination of the Local Plan.
Councillors approved the plans in February last year for the 1,400 homes that had sparked a mass protest march on the streets of Botley.
Protesters fear the development will swamp Boorley Green, change Botley and increase traffic with no infrastructure to support it.
Mrs Grinham said: “This is going to have an effect on future generations.
“We feel extremely let down – the council has betrayed the people of Botley.”
Chris Tapp, of Botley Park Golfers, said the council relying on its own “failures” as justification was “a travesty of proper, responsible planning, for which the council should be ashamed”.
Council leader Keith House said the development would improve Boorley Green, bringing facilities and making it more sustainable while helping protect gaps in other areas.
Cllr House said when told it needed a five-year land supply the council acted quickly and the Local Plan would have been in place by now had Hampshire County Council not taken its site out.
He added that the inspector examining the Local Plan would be trying to find more sites to put in rather than take out.
“They’re clutching at straws. I understand their concerns and fears, but the council has to act in the best interests of the wider community.”