That Technomelt and Moldman look great but they don't talk about the cost of having molds made--I have spent a lot money in the past on injection molds for parts so I would find someone who has used it and ask about total costs, including all the costs for molds and revision to the molds.
You can pot parts yourself with RTV silicone for prototypes or low-volume production. It is a bit messy and you generally need a vacuum chamber to get all the bubbles out, but it can be done. As I said in the other thread, operating temperature is key and working through the heat transfer numbers in advance would be a good first step.
Once again, if the part does not need to meet IP65 submersion, I would recommend you try a conformal coating first and see if that meets your needs since it is so much easier.
If you look at most consumer items that are meant to go out in the weather, they are generally made with clam-shell cases with silicone gaskets around the edge. If your product is automotive, they like to use potting, but understand the design life of automotive electronics is only 10 years and the repair model is replacing entire parts so potting is OK.