Like most people, I have a habit, and that habit is Coffee. Unfortunately, this can be an expensive habit. There are plenty of methods of making it less expensive, but in my experience, most of them are pretty bulky and not conducive to being carried around the country. Others are more portable, but taste dire (looking at you instant coffee, cheap cup from a gas station, etc...)
Assuming the coffee maker in a given hotel room isn't capable of doing anything besides producing hot water competently, how can I make myself a decent cuppa, easily, cheaply, and effectively? What sort of equipment would I want to look into buying or using to do this? Cost effectiveness and ease of use is as important as portability/quality here. I'm open to cold-brew solutions, though hot coffee is definitely preferred.
As far as resources that can be assumed: Hot water and tap water is 90% of what can be relied upon. A fridge or microwave is occasionally present, but I wouldn't count on either.