The splitter from Ireland would cost a lot to ship, but appears to be good quality.
Rest of World
Cost is €30
You can find plastic waterproof enclosures in an electrical supply store. The leads should come out the bottom and there should be a weep hole in the bottom to drain any condensation.
You could buy a UVSJ in an enclosure, and replace the UVSJ with your splitter.
https://www.antennasdirect.com/store...Combiners.html
http://www.mcmelectronics.com/product/33-2230
MCM makes a power passing splitter in an enclosure,, but I have some reservations about their quality control and it will only pass 100 mA current max.
http://www.mcmelectronics.com/product/33-12310