Almost my thoughts exactly. If you want a decent mech mod without breaking the bank, I would go with a well known clone (infinite, hcigar, ehpro).
As for the tank if you want something rebuidable I would suggest a kayfun/russion 91% - IMO a Nautilus/Protank on a mech mod is like a governor on a ferrari.......why?!
This is opinion ^^^
This is NOT:
BUT Before you buy anything, buy an ohm meter if you're going to be rebuilding.
And lastly, research, research, research. You should know all of the steps involved and have a good idea of what the coil you're going to build's ohms will be BEFORE you ever start.
Vape on!