J.H. Reith, E.P. Deurwaarder, K. Hemmes, A.P.W.M. Curvers, P. Kamermans, W. Brandenburg, G. Zeeman. 2005. Report ECN-C--05-008 (in Dutch). http://www.ecn.nl/docs/library/report/2005/c05008.pdf
Table 5.3 contains a literature review of macro algae costs.