My setup at this stage is very basic but allows me to brew AG. The most expensive to date is the mash tun, you can find alot of archived posts and pictures in the gallery which shows guys using converted esky's to mash in. I bought a 10 gallon insulated water cooler and a false bottom. Works a treat. Cost me $180 all up, but I went for ease instead of building one. I'm sure if you build one it may cost considerably less.
I also have the 50L keg and immersion heater. There is no tap in the base, just a hole cut in the top. I boil in that and siphon through a filter bag into my fermentor after chilling. I bought 4m of copper pipe from Bunnings and rolled it around a fuel can to shape, also works well in chilling the wort to 20C in around 30 minutes. I may change that in the future when I learn more about hot/cold breaks, but for now I just want to get my technique right.
We have an older style home (80's) and the hot water system in that is geared hotter than what I think the law permits now. Thus, I just turn on the tap and the hot water straight out is 72C. Makes it easy and not having to have a HLT. One day I will probably purchase an urn, but for now that is fine. If it starts to run a little cool, I simply slowly top up with boiling water from the jug while checking with a thermometer.
I am still a very amatuer brewer, but from what I am learning everyday is that you don't need all the bells and whistles to brew AG. Get the basics to get going and get started and you'll never look back.
Best of luck,
Duff.