Yes, you can convert most LED strips that way. The main decision is whether to use a ZigBee, Z-Wave, or WiFi controller and the various options those controllers have that may be of interest to you. I have never seen an RGBW (or RGB+CCT) controller that cannot control just a RGB strip (nothing to hook up to the white) so you can always future proof a bit. They can even control single-color strips (if you want to control a white-only strip, or a red-only).
My opinion on some DIY Pros/Cons:
Pro - Cheapest possible method
Pro - More possible combinations of what it controls (ex: do you just need 30 LEDs/meter strip (or 60 or 144), just need RGB, need RGBW (warm white), need RGBW (cool white), RGB+CCT, RGB spotlights, etc...) it all depends on what you are willing to do and the same controller can handle MOST of those (most but not ALL are RGBW and fewer are RGB+CCT)
Pro - Buying individual ones means you will NOT be locked into some weird proprietary connector between the strip and controller or it's power supply. Not all sets do this but some do and it can be very annoying if something happens to one (personal example: cat chewing through an LED strip connector)
Con - It will be more time consuming to set up than most packaged sets
Con - It MAY not look quite as appealing as a packaged set, although many packaged sets are just a controller and LED strip in the same box and you could buy them both separately if you wanted
