i use a PAR meter to evaluate the light - this gives me a measure of photosynthetic active numbers of photons/unit-area/second. sounds like you are looking at lamps that are "marketed" for growing, and thus the premium price. I find that regular T5 that is used for commercial lighting, such as a supermarket - warehouse - factory - etc. works 100% just as well as any specialty type lamps.
for example: this $3 lamp will work perfectly:
It is made by Maxlite, and your plants will grow perfectly. Don't worry, I actually have a PAR meter, and I grow all kinds of plants indoors, with a lamp that is exactly like it, except I use a T8 by the same make. 5000K gives plenty of blue: my plants are short, stocky, and extremely healthy! Erin Shine only sells by the case, so it is 75$ plus shipping. Another place to buy T5 is from businesslights dot com, or gladiator lighting. sometimes the shipping can be a bit high so shop around.

Here is a link that might be useful: link to lamp

so, i find the actual brand does not matter. just look at the numbers of lumens, and make your purchase based on that, and do not look at any lamp costing more than $3. (or so).

so, i find the actual brand does not matter. just look at the numbers of lumens, and make your purchase based on that, and do not look at any lamp costing more than $3. (or so).
Your hydrofarm lamp costing $7 will work exactly the same as the $3 Maxlite.

Thanks for the link...very helpful.