Barnet manager Lawrie Sanchez has revealed the club could not afford to hang on to player of the year Joe Devera.
Defender Devera, 24, is joining Swindon on a free transfer after turning down the offer of a new deal at Underhill.
Sanchez said: "He's been a good servant for the club and we wish him well.
"We had hoped he would stay, but when you're a free agent there are clubs that have a bigger budget than Barnet, like Swindon."
Sanchez does not plan on bringing in a direct replacement for Devera as central defenders Darren Dennehy and Anwar Uddin, who both missed large chunks of last season through injury, will be fit.