It's available on HLJ. I find only Otacute being cheaper than HLJ but they don't have it on their website yet. They do list the vol. 18 however, so you could just wait for the time being, it may be added later. ( Amazon.co.jp usually cheapest but they sell out VERY fast on Dengeki Festival's + expensive shipping ). I would never recommend buying from J-List as their items have much higher price tag on them than other shops, and they have expensive shipping too. For example, the mentioned HLJ sells it for Price: ¥3,238 => About USD $40.21; €28.92
Edit : Oh wait, HLJ says Order Stop
. It was available yesterday .... Although the fact that you can't preorder anymore doesn't always mean it will go to Discontinued state once the item is released. You might just want to wait. If you really want the figurine, and only the figurine, you may always try ebay. I'll probably put the figurine on ebay because I'm not too keen on figurines. I want that towel xD.