The price of Artemia cysts went nuts in the mid-90s and has not recovered, partly due to demand from aquaculture and partly due to poor harvests (rain in Utah).
The prices quoted are for top quality (few unhatched cysts, which is great), and quite large quantities - the dry cysts don't weigh much. Store them as batches in airtight containers in the freezer and they keep for years without loss of viability. The one's I'm presently using are at least 3 years old and as good as new. Invest now as I suspect prices will keep rising!