Interestingly, the French troops being stationed/quartered in allied states were also spending money in those countries and helping the local economy.

In most cases the French troops were either quartered in major fortresses, in which case the governor of the fortress superseded the local civilian authorities and extracted supplies from the local populace for the sustenance of the fortress (as well as disbursing the funds that the French extracted from the local civilians to pay for those garrisons); or the troops were quartered directly upon the population, eating their food, taking their supplies, horses, animals, etc.

In the former case, consider for example Magdeburg in 1810-11. The fortress received monthly convoys of supply brought usually by riverboats, offloaded directly to the fortress. These goods were taken from the local populations, or from further afield, and were delivered directly to the garrison. They were never for sale in the local markets. Meanwhile, the French assigned the local people an annual "contribution" for the cost of supplying the fortress, millions of francs annually, plus special appropriations for supplies, taken as needed.

Files related to Magdeburg above, in the State Archive of Lower Saxony, Hannover: Hann. 47 III Nr. 1120 / 1-2.

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I have not seen any hard numbers with regard to contributions to local economies by the spending of French soldiers. If you have any such figures, I'd be very interested.

Rudolph Holzapfel (1895) mentioned that there were a few periods during which retailers of luxuries like tobacco and coffee did a brisk trade, but of course only when those rare colonial goods could be gotten by civilian merchants and after 1807 that was increasingly rare due to the blockade and embargo.