As someone with few resources, I can only do market research through observations, talking to people and using google questionnaires in addition to finding secondary research done on the topic. However, is this method of "market research" acceptable when I want to present my ideas to potential investors? Is there some sort of more valid form of market research?
There are a lot of things someone can do to do market research with few resources.
1) Internet is full of data already collected ready to be used: google trends, searches, keyword and queries analysis can already give you an approximation of "what to search". Tools like Ubersuggest, Buzzsumo, but also Google Keyword Planner, and hashtag research on Twitter and Instagram help a lot.
2) when it comes with products Alibaba, Aliexpress and Amazon can help you see what the world is buying: trending products, best selling products, most rated products...
3) More specific websites like Statista, where you can start from free but then you will have to pay
Internet IS data! Everywhere