Sounds like you are where I was four years ago. Same goals, same vague idea of where to start. I guess it's pretty natural to concentrate on how to get a pot full of molten metal as your starting point. However, you will need some place to pour that melt, a mold preferably. Thus you will need a flask, a bunch of sand, and a pattern. Oh, and a core will likely be needed also.
My suggestion is to pick a simple first project, for me it was a 1lb. scale counter-weight. Think through each phase and make a list of things you will need, having done that it's easy to spot great deals. Create spaces dedicated for specific activities such as an area for making sand molds, and area for creating patterns, etc.
My furnace is a Lionel Oliver kit and it cost me around $300 to construct if memory serves me right. I'm melting 10-15 lbs. of aluminum using propane. I can pour, machine, scrap, pour again and machine in one day. I can make a core in two years, tops.
So, enjoy the journey. It's going to be fun.