During its initial negotiations with Murray, Naturalis obtained an option of purchase, the eventual buying price to be determined by the completeness of the skeleton. When more and more bones surfaced, it became clear that the museum had endeavoured on a project of considerable cost, estimated at seven million euros in November 2013. Only one million euros could be covered by the institution's financial reserves. The remainder was raised by a combination of private gifts, municipal and state subsidies, and charity donations. Naturalis promoted a "Tientje voor T. rex" (Tenner for T. Rex) campaign to raise funds for bringing Trix to Leiden. About 23,000 individuals, mainly children, contributed ten euros. About sixty companies "adopted" a bone. Late 2014, the purchase could be made. The procurement costs, including preparation and legal advise, were indicated at €4,291,466. At that moment, Naturalis owed the BHI €1,027,556.Naturalis Biodiversity Center, Financiële Verantwoording 2015 56 pp These numbers did not include the costs of exhibition and promotion.
