That right there is not true. You do not know the ph of the water you are using, unless its that bottled type that straight up says "PH 7" which still isnt ideal. Im running a low budged grow too, thought ph wasnt a huge issue. I decided to take the plunge and buy a meter. To my surprise, my tap water (yes, after I had left it out for 24 hours++) was testing at a solid 8.2. Yeah. No where near a good ph to be watering plants with. After I added my nutrient mix it was still at 7.5. I now use ph down to keep it 5.7-6.2 range. Its totally worth it imo. It'd be dumb to end up causing a lock out or other ph related issue,which a larrrggeee portion of plant "sicknesses" are ph related, the number one response to posts in the marijuana plant problems section is: "have you checked your ph?" There are multiple cost effective ways to solve this, amazon sells digital meters for as low as $25.
tl;dr Save yourself the trouble that your gonna encounter later, just buy a meter.