First of all the term pre-patent research is vague to me. I can see two main meanings of the term: 1) research as to whether your product would be feasible from a technical or economical pojnt o view and 2) research as to whether your invention would be deemed to be patentable.
Since the first is just a feasability reasearch - and although you mention such an example in your question - I assume that this is not meant by the term 'pre-patent research, because in principle the word patent then would be misplaced.
This thus leaves the meaning of research into the patentability. Again two possibilities are included herein: 1) whether the invention fulfills thecriteria of USC 101: is it patent-eleigible; and 2) whether the invention fulfills the criteria of USC 102 and 103: is it novel and not obvious?
For an answer to the first question you should get legal advice from a patent attorney. For an answer to the second question you need a patent information specialist to provide a prior art search and maybe a patentagent or patent attorney to interpret the results of such a search.
Companies that provide patent searches are abundant, as well as in the USA as abroad (e.g. India). I would suggest to contact a patent agent or patent searcher to find a reliable one.