Principals are being urged to scout for bargains on eBay after one college saved nearly pound;50,000 on computer equipment by bidding in an online auction.
The thrifty college bought the "high-spec IT equipment" for just pound;250 -plus postage and packing - when it would cost 200 times more new.
The Learning and Skills Network called on other colleges to follow suit, after uncovering the shrewd deal in a survey of environmentally friendly practices by colleges.
It found that Sparsholt College in Hampshire was buying computer servers dumped by big corporations and refurbishing them, making huge savings.
Buying second-hand is also considered less wasteful and kinder to the environment, the report said.
The survey of 151 colleges was commissioned by the Learning and Skills Council as part of the FE funding body's efforts to encourage "sustainable development" in colleges.
The council is putting pressure on colleges to draw up plans for conserving resources and energy and is increasing capital funding by 10 per cent, ring-fenced for new environmentally friendly building design.
So far, more than two-thirds of colleges have completed audits looking at their use of resources.