Establishing the market value of art is a known challenge. A traditional distinction between primary (first-sale) and secondary (re-sale) markets in fact relates to two approaches to value-estimation and pricing: that of the gallery and that of the auction house, respectively. To overcome this dichotomy, we propose a novel rating system for the actors of art markets, equally adaptable to primary and secondary markets. We introduce a time-aware variant of the HITS Web ranking method, which captures the interlocked role of artists and collectors and rapidly adapts to changes in the relative importance of the actors part of a market. We apply the proposed method to crypto art, a novel form of born-digital art exchanged on blockchains, and show that the proposed method outperforms alternatives when used to guide market investment.