I usually start by finding the mfr part number(s) and then do a google search on them. Prices can vary quite a lot and they fluctuate from time to time. My last two sets of EBC Yellowstuff were from Amazon, since they happen to have good prices at the time, but I've bought from other sellers too.
I am not a fan of drilled and/or slotted rotors. Any machining on the rotors compromises structural integrity and will induce thermal gradients, which will invariably lead to stress fractures. Unlike back when brakes pads used to off-gas, drilled/slotted rotors don't add much performance benefits these days. Still, folks have grown accustomed to liking them for the racy looks. Nothing wrong with that, if that's why you might want them. For typical street applications, they won't get stressed/hot enough to cause thermal cracks for the likely duration of their service life.
I personally prefer solid vented rotors. The OEM rotors are made by Brembo and of excellent quality. If I were to "upgrade", the first path would be directional rotors, with internal vanes are that optimized for air flow for either LEFT or RIGHT side rotation, so they are always sold in a matched set. These typically don't cost a whole lot more compared to OEM rotors. From there, the next upgrade will start to get a lot more expensive... and that is two-piece rotor. For street applications, those are a bit extravagant, but some folks don't mind spending the $$$. IMO, it's still money better spent than on spoilers that don't spoil, splitters that don't split and diffusers that don't diffuse. But that's just my own $0.02. Everyone has their own cost vs. benefit calculus.
If you are talking about the brake pad material deposits on the rotor... yes, cleaning them off do tend to reduce the pulsation when braking at speed. How long that lasts and whether it is worth the effort or not are a whole 'nother matter. Unless you change out the pads, they are just going to leave deposits over time again. It's not my place to tell you what your time and money are worth.