In 2012, The NPGS [the US National Plant Germplasm System] budget was approximately $47 million. Funding for the NPGS has been relatively stagnant over time. In real terms, agency funding peaked in 2003, at approximately $53 million in 2012 dollars (fig. 1). While direct comparisons between costs of a genebank and its benefits are not possible, ((Emphasis added.)) for context, we note that U.S. farmers paid $20.3 billion for seed in 2012 (USDA\National Agricultural Statistics Service, 2013). Thus, the costs of public ex situ plant conservation in the United States are a small fraction—under half of 1 percent—of the value of the eventual seed market. At the same time that budgets have decreased, demand for NPGS germplasm has reached historic highs (fig. 2).
Gotta love it when economists give up on quantitative data, and settle for qualitative comparisons.
When compared to the rather large benefits of genetic enhancement, the costs of genebank operation appear relatively small.
But do read the whole of USDA’s Using Crop Genetic Resources To Help Agriculture Adapt to Climate Change: Economics and Policy by Paul W. Heisey and Kelly Day Rubenstein. There is some data in there, and that perennial fall-back of economists, a model. The main findings, if you just want to just skip to the bottom line, were that genebanks are worth it, but that better data and some pre-breeding would help.