Hummels are a very special case - they have long passed their status of being "collectible", ergo the prices have turned foul.
Example: "Smart Little Sister TM4" is often offered for around US$ 310, the same edition is offered on eBay for around US$ 160 ... but the truth is that they hardly sell for US$ 30 - US$40.
Goebel was shooed into the doghouse for actually admitting that they wanted to manufacture in China and then only decorate the figures in their factory. At the same time, former club members were found to have been involved in dubious proceedings regarding "unmarked Hummels" (which de facto do not exist). That was followed by Goebel filing for insolvency and then going bankrupt in 2006; subsequently the Hummel rights were sold to the Porzellanfabrik Rödental (which is by now also struggling for survival). Since 2007, many former collectors have been dumping their collections. Some stores and online venues try to keep up the old prices, but real "street value" (found in closed auctions or closed sales) is *far* from what was once paid for these figures.
Hence buying Hummels for resale is a very tricky matter. I just hope you can get a little profit out of your purchases.