It has been observed that ordinary covers posted at Foreign Post Offices in China (mainly French and German POs in Shanghai and particularly during the China Large Dragon-Small Dragon-RR-Dowager era) with Foreign PO stamps are fetching very good prices compared to one year ago.

Are there more people collecting FPO in China? May be, but............

It has also been noted that there are increasing number of China-Foreign PO combo covers in the stamp market, eBay and public auctions, being offered compared to a decade ago. Many of these "offers" are good fakes and sadly, many are selling at good prices to unaware buyers thinking that they have bought good bargains particularly on eBay.

Possible reason:-

That the buyers could be buying raw material for adding fake "Classic China stamps" and fake Customs chops to make fake combination covers; such covers could sell for many times the original price on eBay or at Public Auctions.
Forged Chinese cancels (Dollar chops, Seal chops, Customs daters, bi-lingual cds) are now getting very difficult to detect even upon close inspection because the forgers are using sophisticated equipment in producing fakes cancels. It is now almost no longer possible to detect whether the cover is fake on the scan alone. Even cancels of Foreign POs and arrival baclstamps have been extensively forged.

Furthermore, it is believed that the forgers have already produced convincing looking fake Classic China stamps using fake watermarked paper in some quantity. Using these fake stamps would reduce the cost of making fake covers.

Remember: What's too good to be true usually is. Caveat!