Full-text of this article is not available in this e-prints service. This article was originally published [following peer-review] in Online Information Review, published by and copyright Emerald Group Publishing Ltd. The pricing tariffs adopted by the online hosts are full of hidden complexities, such that it is difficult to estimate in advance the cost of online searching. Potential elements of costs are: subscription charges and discount plans, connect time charges, display/print charges, telecommunications charges, session rates, charges for special facilities and charges for special services. The complexities of each of these elements are considered in relation to a number of online hosts. The review offers an insight into the estimation of the costs of online searching.