Mato has a lot of upgrade parts available as well. They make all their own all metal tanks so this means they have metal parts to totally rebuild a Stug, PZIII, Tiger, or Sherman. The Sherman rotor shield and Mantlet for the 75 mm Sherman is one of my favorites. For stock inexpensive Heng Longs they are one of the best online retailers, that try to make things right if you have a problem.
Your question about what you got yourself into depends on you. It is a very diverse hobby, that has a historical significance to it like no other RC hobby other than flying, increasing the enjoyment level. It offers electrical, mechanical, and accuracy challenges that should keep the fires burning and the boredom away,.
I know it captivated me and pushed every other hobby interest I had to the sideline.