Ann: Sinclair Mine Complete, First Caesium Shipment Scheduled, page-37

The simpler way to view this is to take the amount of ceasium, which is quoted at 1640 tonnes of pure ceasium and then apply the conversion ratio of pure ceasium needed,to make caesium formate as commercial product.
That ratio is 1kg of ceasium will produce 1.67kg of product, so the theoretical yield of caesium formate will be 1640t x 1.67 = 2739 tonne
Then apply the great unknown, which is what Cabots charge for a tonne of caesium formate when the customer loses some of their rental caesium formate product. 
Using the original 25K/t and Cabots have product to the value of $68,475,000 from Pioneers stash.

Maths on how the ratio is derived copied in from an earlier post 
The next question is to consider is, how much cesium is in the commercial cesium formate product. The cesium is diluted twice, firstly by the reaction with formic acid to create cesium formate and secondly when the cesium formate is diluted with water to produce the commercial grade product.
1) The formula of Cesium formate is CsCOOH, mole weight of ~178, which can be split into the weights of it componentsCs = 133 C =12 O=16 O =16 H=1 (133+12+16+16+1=178)So it can be stated that 133 mol of this 178 mol product is cesium (178/133=74.7% is cesium)From that 747 grams of cesium are needed to make 1kg of 100% pure cesium formate.
2 )100% cesium formate is then diluted with water to 80% strength, so the 747 grams becomes 598 grams (747 x 0.8 = 597.6) So if 598 grams of cesium will make 1kg of product, then 1kg of cesium will make 1.67 kg of product.