Simple equation, figure out what you think is going to cost and then double it and you will be about on the money. The big things are easy to figure out (fridge, coffee machine, grinder etc) but there are so many things you just dont think of and they add up. The final figure also depends on a number of factors as to how you set it up and what extras you will be doing (on top of hot drinks ie smoothies). I would allow around 20-50 k depending on what sort of a setup you are aiming for. When you are looking at franchisers and established businesses you are paying for the work that someone else has done, if you think you can do it yourself then you will save yourself a heap of dough but you will be on your own without support and the business will take a while to get moving, your call as to if that is important too you. You have to do the work and figure out what level of success is necessary for your personal circumstances (ie how much money do you need to make to cover your living expenses) and then work out how many coffees per week you need to sell and then talk to someone in the industry to find out how realistic you are being.
Also get friendly with your council (or whoever enforces food safety standards) as they can be your best friend or worst nightmare.
Good luck with your venture the rewards are there if you are prepared to work hard (and trust me sometimes you will question your sanity).
Also do a search as this is a question that has been asked and answered in a lot of details over the past couple of years.