Anyone from the student community can sell a product by selecting the category link. If the category doesnt exist, place your offering in the miscellaneous link.
Under the category link, place the item in the comments section. Please mention as many details as possible, expected price, your contact details, last date for sale. These things are mandatory.
You wouldnt be able to view the comments but your offerings will be uploaded under the category asap for all to see.
The potential buyer can get in touch with the seller and make the necessary transaction.