The jointer will give you a flat surface to put against the fence of many other tools. Band saws will allow you to rip the wood to the dimensions you need. The table saw (most important tool) will handle all crosscuts and many finishing cuts. The Planer will make the top and bottom of the wood parallel. Planers can reduce the width of wood in very fine increments.

that's at least $700 in tools!

It may seem like a lot of money, here's some perspective. I made a door for my mother for Christmas, the wood cost $100, it cost $40 to get it milled to size. The project I plan to start this summer is going to run around $400 in wood. -- That's 160 in milling costs. Many of the tools do multiple things. I recommend purchasing one tool at a time, when you can afford to. I would start with a table saw, and upgrade as the need arises. Bandsaws are great for bent venire projects and cutting assembled projects. Planers and jointers are mainly used in the milling process, but have many uses when preparing to assemble a project (butcher blocks). There are also many specialized power tools that are incredibly useful.