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?
Hi - the best market research to present to potential investors for a start up is revenue generating customers. It is possible that you are at an idea state. I doubt you will get funding without customers, a minimum viable product, and a revenue model, no matter what market research you may submit to them.
Market research through observation for a small business is perfectly acceptable if backed by a working business model.
Hope this helps.