One-stop shopping, fast delivery, cheap as possible...choose 2. That's coming from China, so the quality of what you're getting may be decent/good, or you could be getting cheap knockoffs. It will also take some time getting here...plan on 2 weeks minimum possibly even longer as there's going to be a back log of shipments due to the Chinese New Year wrapping up. Finding reviews from previous customers who has used that particular merchant, or buying from "trusted" sellers is often the way to go, but you may end up paying more for a trustworthy source. But your odds of getting a better part increase, especially with electronics. For instance, I didn't know better when buying my heated bed and went with the cheapest I could find, only to find out that the resistance is signifiantly below where it should be, forcing me to drive the MOSFETs on the RAMP harder, likely shortening its life (part of its magic smoke already escaped). Spending a few bucks more up front likely would have saved me spending more than a few later when I have to replace my RAMPS board.
Part of the fun though for me when I was building my printer is finding all the stuff that I needed. You get to visit a lot of different merchant sites, some good, some bad, but you get to see what all is out there. Maybe you don't want mechancial end stops. Maybe you'd rather have optical. Or Hall Effect. Or maybe instead of T2.5/T5 belts, a GT2 is better (or worse). What size pully is good enough, why is a larger one better, etc. Getting a BOM (bill of materials) for your particular build, setting up a spreadsheet so you can record where you're find things at a particular price, and figuring what exactly your budget is will help a lot.
