In China, there are 10 <a href="http://www.injectionmoulding.org/">injection moulding</a> companies who manufacture Bakelite handles like my company. And there is only one phenolic moulding compound manufacturer nationally. Their capacity 200tonnes/month. However, they export much more than they produce. I am investigating this issue about two years. Their production cannot work alone in the plasitc injection moulding machines. So, we always have to mix the local one and the exported ones. There is no stable production in this field. I also tried to get these answers from the Chinese injection mould manufacturer. They are not sharing information naturally. Also I asked some professors in chemical engineering but this field is not popular and is not well known. It is worth to know, if I cannot find the procedures and all stuff of this project I am going to start the have them in chemical engineering.
I work with a plastic injection moulding company so my answer below will be based around the availability of resins for thermoforming and not necessarily injection moulding. You mentioned this being for an electrical part. Are there any anti-stat or Electro Static Dissipative properties that need to be considered? Once you start getting into the 350F temp range, your choices get somewhat narrow and the moulding cost goes up tremendously...especially for ESD materials. Injection molded Nylon will be about the cheapest high temp plastic. Your PEI, PPS, Polysulfones and the like are going to be extremely expensive. Your best bet is to determine which properties are important and then go to the website and use their plastics moulding calculator. It will allow you to input your properties and then will suggest materials based on those properties.