Hi...
I've bought 2 sound triggers and a laser trigger from a guy in Greece on Ebay. Haven't used the laser trigger yet but the sound triggers do the job for under a hundred $. One of my sound triggers has a no bounce feature so you don't get multiple firings if the noise repeats. Some name brand triggers cost hundreds of dollars. This one you've found seems to have everything you need in the one box as long as all the accessories are included and if it has an adjustable delay time. I just downloaded and read the manual and it does.
One of my sound triggers needs the mic to be close to the sound and if water is dripping, the mic tends to get wet so if the external mic is on a long lead, this is better to keep the main unit away from water.
Hope this helps...