Monday Hour One and (intentional/purposeful) online shopping

Thinking about Monday Hour One and researching an online purchase. How would I go about setting a specified time frame for this? It seems as though some things are easier to research than others and I may not know until I jump in. Would I plan a very brief “pre-research” session to get an idea of how many options there are and therefore how much time I might need? Sometimes there are too many choices and sometimes too few. With too many, it’s easy to feel like you should check them all out or at least several to understand what features are available and therefore how to sort the items and rank and decide what to buy. With too few choices, sometimes I want to go looking at other stores/sites to get a few more options.
Just wondering about other ideas for reining this back so I don’t “accidentally” spend much longer than I want or should.