You don't want the cheapest. Cheap shit begets cheap shit. The most expensive portable I've bought has survived twice as long as any other and is still running to this day. 24/7, for over 12 years, no repairs, except that the original GFI plug fell victim to flood, GFI replacement lasted 7 years and was just swapped out again by yours truly. That bitch is a work horse.
You do not want a portable for bloom, veg only.