If budget is what's driving you, DIY is where it's at. I have absolutely 0 knowledge on anything lighting. I mean none, I'm a plug and play kind of guy. But I too wanted cobs, so with a lot of research and 100,000 questions about anything to anyone that would answer I set to build my own. And after 1 rough trial with citizen clu048 1212 cob chips, I set out to build something cleaner with bigger cobs capable of handling more power. Finally settled on citizen clu048 1818 on meanwell hlg 185 - c1050b's running each cob at roughly 66w.
The cobs can be had cheap for about 20$ a chip for 90cri gen 6 chips. It all sounds fancy that just means "top shelf" with not so top shelf chips like my 1212's available for as low as 8$ a chip. 1212 are good cobs also just smaller in terms of output and all that jazz. What I'm saying is cobs can be had for a lot less than you think.
I may have 7 - 800$ total in my lighting. That's 550w of cob spread over 9 chips. That's around what you can buy 1 name brand cob light for, aside from sm0's stuff which is relatively cheap for a plug and play option on single cobs.
@Hypathetical Gardener feel free to get in my inbox if you want some links to cheap stuff or to ask your own 100,00 questions lol