The college withdrew from the site in 2010 after finding that it would cost £830,000 to bring the buildings up to standard and comply with disability access legislation.
The gardens have since been maintained by Friends of Suntrap volunteers along with the college. Co-owner the National Trust for Scotland allowed campaigners two years to produce a business plan for the site.
Oatridge principal David James said any business plan from the Friends of Suntrap would have to produce the best value for the college.
The Friends of Suntrap left the site on 31 July and the site is now on offer through property services company DTZ, which is looking for offers in excess of £305,000.
James stressed that a number of parties interested in the site wish to maintain Suntrap in its current form, with some considering keeping it open to the public.