Can any household time be used for my 175w MH or do I need something special? What should I be looking for? I don't need anything fancy, just an appliance type timer.
You should be able to use any timer. Just make sure it is grounded. Many of the cheaper models are not. It's usually the "heavy duty" ones that are grounded.
I bought one of the Heavy Duty appliance timers at HD. They are grounded. I have three 175W MHs plugged into that one timer. According to the ratings on the packaging, I'm not even using half of the wattage capacity of the timer.