I was wondering how expensive would going into tech be?
You know what they say - if you have to ask, then it's too expensive.... ;-)
But at the risk of saying stuff that leads to flame wars, depending upon what compromises you are willing to make, you can manage the costs. If you are willing to dive deep air instead of helium, you chop a huge cost off your "per dive"expense. Some people think deep air is OK (within limits), others think it is suicide. You can cut tables instead of buying an expensive tec computer (or two!).
And tec givers always seem to accumulate much more gear than is strictly needed. Whilst it is not mandatory to have two dozen tanks, about fourteen regulators and four different sizes of wings in your garage, it just somehow seems to happen when you get into tec...