FWIW, and I'm only saying this because the OP's on a budget, I don't ph and never have troubles. It has appeared to me that soil has far more "gravity" (buffers) to pull the nutrient solution's ph to it (than the other way around). But, this depends on the water's mineral content, the strength of the nutrients. (If a person feeds strong, then the "weight" of the solution may affect the soil.). It may depend on whether the soil has dolomite added (I add 1-1.5 Tbsp per gallon of soil mix. I use Fertilome Hi-Yield Agricultural Lime.). It may depend on which nutrient brands are used. Maybe I'm just lucky. (But, I've seen others say they stopped ph'ing, and no problems.).
A ph pen, calibration solutions, probe cleaning and storage solutions... it adds up. The OP may want to take their chances. (My life feels much easier without ph'ing. But, again... maybe I'm just lucky.).
The soil goes through a fairly wide range of ph between wet and dry too. As long as there isn't salt buildup in the soil (feeding too strong, not enough runoff), that range should be healthy unless the soil has a bad ph to start with.
Also, to help the soil dry, the OP can get a 1/4" aluminum rod at the hardware store. About 18" long. Put it in a drill, spin the opposite end against a steel file to make a rounded point for less damage to the roots. Then bend about 4" (of the other end) 90-degrees to make a handle. Use that to aerate the soil. I use this a lot in flower when the soil is compacted (which, sometimes I wonder is due to too much magnesium). That could be a way to help the soil dry faster without disturbing the plant (trying to get perlite into it). The aerator doesn't have to be as fancy as I made for myself. It could be a coat hanger. Just stiff enough to push into the soil. For me, at this stage of growth, it wouldn't be hard to push a wire coat-hanger into the soil. But, in flower, I need something stiffer. (I wouldn't go crazy poking into the soil. It has to be a balance between improving the root zone versus tearing it up. 5-6 holes can help it dry, drainage.).
To the OP: It would help to know your water quality. If you're in the US, water providers are required to publish an "annual water quality report." You can usually find it by googling. If not, you can call your water provider and ask for it. (Or, if you're not in the US, they should be able to tell you about the water quality.). You need to know the "TDS" (total dissolved solids) in your water. And, what they are. If it's high (above 200... but maybe you could live with 300), you should take steps to correct that. Or, if there's some kind of imbalance in the minerals, that would be good to know about before you have problems.
Eventually you should have a PPM pen. You can get them for $20 on Amazon (last time I looked: EZ-TDS or TDS-3). You don't need calibration solution. You can mix[1] 1 gram of salt (from the kitchen table) to 1 liter of distilled water. That's 1000ppm. If you had a pen now, that would tell you the total PPM of you water. But, you'd still need to know what those PPMs are (by finding the water quality report, or calling your provider.).
[1] I have a Horizon PRO-20B. It measures up to 20g with 0.001 resolution. Costs $22. But, that's more precise than necessary. I have a Horizon HB-01 (100g with 0.01 resoluton). It costs $12. That's plenty good for weighing the salt for the PPM calibration, or your nutrients if you mix different products together. A company called "anyvolume" sells these.
