Hey there Fishymamba!
I say, find the nearest bicycle co-op and confer with them as to what type of MTN biking you want to do. Decide upon the best type of frame design that will suit the type of riding you wish to do. Next, research MTB frames. Checkout Jamis, Surly, Voodoo, Salsa, SOMA, etc.
Once you've purchased your frame, you can purchase, swap, or barter for components. Most probably the co-op will have a few really nice components available, as well. As you save your money for the purchase of the next component, study the correct procedure of the installation of that particular component. Read books and related literature. Talk to the co-op mechanics. Watch related videos using your video search mode. Study the material and watch the videos as many times as required, so that you may be proficient at the installation. Eventually, you will see your brand new MTB form before you. At the end of this venture, you will not only have a brand new MTB, but you will also have acquired a certain degree of bicycle mechanic proficiency.
If you stay close to the co-op and become a volunteer for at least one day per week ( like on Saturdays). You will find that your mechanical skills will increase almost exponentially.
Here is a link to a few MTN bicycle frames:
www.universalcycles.com/shopping/index.php?category=2154
Good Luck!
- Slim
PS.
Most MTN bikes are made of aluminum. You will have the opportunity to select chromoly steel as your MTB frame. You will not only have access to the traditional chromoly types of steel, such as 4130 and 520, but you will also have the choice of selecting premium grades of steel frames, such as 631 and 853 chromoly steels.