What are you welding that you need TIG? If you need the best welds possible do you think you’ll get that with a make-shift TIG welded? There is more to it than power supply, torch, foot control, and high frequency. What about cooling, thermo projection, duty cycle, valve for gas, how about a cabinet to put it in. Last is safety. If you have ever been bit by HF you learn that you don’t want to make that a habit. If you weld with a Miller 175, 210, and 255, you’ll see that you get what you pay for. The same goes for TIG welders.
Save some money, get a tank of C25 and use that. Then save some more money and get a plasma cutter.