What? You can get all of the parts for a CuBr laser on eBay (Although many may be more convenient to buy at your local hardware store...). The hardest part to find is going to be a suitable vacuum pump. Alignment is going to be easy - Copper Halide can even lase without any cavity mirrors - although many designs use a silvered mirror for the HR and either no OC or just a piece of plain old glass for the OC.
You're forgetting a laser crystal for the fundamental wavelength that also has the correct coatings (also expensive, especially for Yellow). Pump diode, potentially pump correction optics, diode driver, temperature control, something to mount it all on (plus adjustable mounts for the ideally both mirrors and KTP. Sourcing KTP/YAG/Whatever coated for Yellow isn't going to be easy. Green is fairly straightforward and fairly cheap. Yellow not so much. I'm not even sure what process is being used by CNI to produce 577nm - I'm seeing references to OPSL and frequency doubled Yb:Fiber lasers - neither of which are as simple as you make out.
Sure, every component of the power supply straight from ebay, easy peasy (slight sarcasm). Then there's the tube crafting, getting the proper temperature, pure Neon, decent Cu/CuBr/CuCl, and getting all of it to behave together. Sure, the alignment isn't a problem, and I've already got a mirror/window set just waiting to be put to use, but crafting a CuBr isn't necessarily an overnight project.
Though maybe I am greatly overestimating it since I was never able to get around to it. The managers of the dormitory I live in get farily upset when they see untidy living conditions.
For some reason I was basing my response on the idea of recreating a 561nm - I have no idea why...
I didn't mention diode and driver, or any other item you'd need for all solid state, because I figured they went without saying, I was only listing to difficult to acquire parts. In the case of 561nm, the gain crystal really requires nothing special. As long as it's broadband IR HT, you're golden, pun intended. The external optics and KTP however would need to be specially produced.
For 577nm, I do not think CNI is using the OPSL method. The Coherent 577nm OPSLs are available up to 3W - CNI tops out at 100mW. They also label the devices as "Solid State". So unless CNI is labeling OPSL under the solid-state category, I'd assess they are ussing a different method.
EDIT: I did almost go through with the TEA CuBr idea, just didn't want to pester my suitemate with the loud clapping of the TEA... Even posted about it at some point on here. It is now part of a long list of "to-do's"