As a Motorola Razr user, I will give my opinion. To my knowledge there is only three main players in the market. I think most potential buyers for the product are more inclined to visit these websites directly for the time being. I can honestly say at the moment there's no real advantage to a folding phone. Sure it's more compact but the weight is generally much heavier due to the folding mechanism but I am impressed with the screen, once opened you can't really tell the difference.
The market is there but it is not great. Even though it's a whole new generation I've noticed people still refer to them as flip-phones. So as for the domain, yes even I looked to see if it was available about 6 years ago. Personally, and for the time-being, the term has passed its interest peak. It will come again but only if many manufacturers enter the market.
I think you would have got your best price around 4 to5 years ago. when it was a hot-topic. Today, I won't give you my price because I think you'll be totally disappointed. This is a term that you'll have to hold onto to see if the market really takes off, instead of just the interest. You need at least nine to maybe a dozen different players out there for the generic term to hold credence to my mind.