Here are some things to consider:

Consider looking for a pre-made or pre-existing solution that could be customized to meet your needs.  This would require some Googling, which I have started, but have not found anything yet.    This will seriously reduce the about of time required to code an brand-new solution.

If the absence of a pre-existing or pre-made solution.. a custom coded solution would be feasible, but I would recommend:

• Remove the private message exchange feature.  Instead provide the ability for people to supply an email address or social media contact (FB, Twitter, Insta, Snap, etc..) that people can use as a way to privately converse and meet up to exchange the item.

• Absolutely make sure that this is available ONLY to UT students, staff, and faculty.
• If you open it up to the outside, you unfortunately will gather the interest from internet trolls, malicious actors, spam, etc.    
• Require UTEID logins to even see a list of available items, manage their listings, etc..
• We can utilize Enterprise Authentication (what you see when you attempt to login into the various UT online resources).

• Make sure your solution provides lots of information about alternate methods such as donating to T2T, information about free outside exchange sites like “OfferUp”, “FreeCycle”, and others.   This could be a “static” website with all kinds of information, and then provide links from there to your list that people can visit. 

• Be very careful about and make a very clear about money exchanges and provide guidance about how to exchange money (you do not want to facilitate this, instead leave that to Venmo, Ca$hAp, and others) and safety about meeting up in public places, etc..

• Decide how you want to handle the item retirement?   You are going to have lots of students who are not going to want to jump through hoops once an items has been exchanged to remove it from your list.   
• You might decide to have items go up with an expiration date.  They can be reminded about the expiration date, and if they do nothing (ie, they do not proactively log in and renew the listing) then it would be removed.
• Another option would be to have an easy “Remove” button, so there is no confusion.

Success of the project:

• Work with UT Housing, Admissions (for freshman), and possibly off-campus housing companies try to partner with them to ensure that events and resources are communicated to student through formal channels and official communications.
• Work with UT communication and whoever is responsible for the human fronted kiosks to ensure people are again aware of events and resources that students can ask about.
• It sounds counter-intuitive about waste, but sometimes a smaller amount of waste will greatly reduce a large amount of waste such as advertising, or careful placed flyer or posters to help inform students.  
• Partner with UT COOP store and others where they can provide information to student who come in and ask (if money is tight, or can not afford items in store) where the events and resources can be found.   Have them provide a website (the one you are going to create) or a small slip of paper that gives those resources.