The first thing you are going to need to invest in if you want to build a great home studio these days is a high quality computer with plenty of hard drive space and lots of RAM. Luckily high quality computers are getting less and less expensive. I recently bought a PC with 8GB of RAM for just $800.
After you get your high quality computer (you may already have one that will get the job done) you need DAW software (DAW stands for Digital Audio Workstation ) that you will be doing your mixing and recording with. The so called industry standard is Pro Tools but it s definitely not the only choice (or necessarily the best choice.)
What you get after that initial purchase of a computer and a DAW really depends on what kind of music you are interested in making. If you want to make entirely electronic music with no recording of vocals or real instruments then you may want to look into various plugins at this point but most people (even those doing mostly electronic music) will want to be able to record vocals and instruments and will need some sort of audio interface.
I should note that many audio interfaces come with a basic DAW program so you can kill two birds with one stone when you buy your audio interface.
So what is an audio interface? To put it in the simplest possible terms, it s the in between between your audio inputs and your computer. Personally I use the E MU 1616M and I highly recommend it for those on a PC who don t need a lot of inputs. But there s really a huge selection of audio interfaces available, it s too big of a subject to cover in detail. Again the industry standard is Pro Tools but that s not necessarily the best way to go.
Another must have for most people is a microphone. A good quality microphone will allow you to record vocals and all sorts of acoustic instruments. It will clearly be a very important part of your home studio. If you can afford it, I would recommend checking out the Shure KSM44. I ve been using this mic for years and I very highly recommend it.
Your audio interface will have a built in preamp that will be good enough to get you started, but you will likely want to upgrade to an external preamp at some point. One very cool (and very affordable) option is the ART MPA Gold. It allows you to get that sweet tube sound for just $300. Plus it gives you two channels to work with. On top of that, many people replace the stock tubes that it comes with and get an even higher quality sound quality by doing so.
Once you get all of this gear you get to the really important part of recording music, learning how to use it! Recording and mixing music can be a pretty complex thing so if you are new to it, I really recommend getting some books on the subject to help you through the growing pains.