10 of these are 40,000 service, which seems to be valued at 1 pence each, as most of these event currencies are.

At the cost of 400 echoes worth of service, and 2 revolutionary favours, I get 100 echoes worth of scarabs, 625 echoes worth of Ray Drenched Cinders, plus an additional 62.5 echoes from getting a single rare success to snag a free Searing Enigma.

That's 787.5 echoes, 725 without the Enigma (I'd give the chance of one a value, but I have no idea what the odds of that rare success are). That nears double the value of most of the other options about 1.81 pence per service without the enigma, with the second best being the Polythreme Ammunition for its ability to be sold at the Rat Market, which boosts it to a mere 1.28, and the third best being the wines for their ability to be sold in the Khanate for Crackling Devices and then sold to the Rat Market, which is a mere 1.265 PPS,

I'd say they have a very good idea of what constitutes generosity.