Unipol is owned 40% by the University of Otago, 40% by the Otago University Students Association (OUSA) and 20% by the Otago Polytechnic Students Association (OPSA).
The facility has outgrown its leased home in Anzac Ave and discussions are under way about building a new facility at Logan Park or, the most likely option, adjoining the proposed Awatea St covered stadium building.
Building a new gymnasium would future-proof the facility but would come at a cost.
OUSA president Simon Wilson said yesterday a figure of $12 million-$20 million had been suggested, but this was a "guess".
If the guess was correct, OUSA might need to contribute $3.6 million-$6.8 million and OPSA $1.3 million-$3.5 million (their shares after company assets were taken into account).
OUSA had a capital reserve fund of $3 million, but Mr Wilson said the interest from that money was used to help pay for operational expenses.
"If we use that capital reserve we will have a deficit in our budget."
OUSA would also have to take out a loan to fund the remainder of its contribution, which would affect its revenue for many years to come.
Asked if he thought it was worthwhile for OUSA to invest so much into a new Unipol, Mr Wilson declined to comment.
"I won't speculate on that. It is not likely to be a decision I have to make." (His term as president ends in December.)
OPSA co-president Ryan Ward said the association had "substantial capital reserves" - he would not say how much - but the executive was still discussing how much it could afford.
"We would be stupid not to go with the rebuilding idea, but we hope our share of the costs would not be up around the $3 million to $4 million mark. We haven't seen any serious figures yet, so we just don't know."
The Carisbrook Stadium Trust announced on Sunday it was about to call for expressions of interest from construction contractors and suppliers.
Yesterday, trust chairman Malcolm Farry clarified the expressions of interest were only for the part of the stadium being built by the trust.
University chief operating officer John Patrick said it was too early to give the construction timeline for its facilities, which will adjoin the western wall of the stadium.
