Also, you haven't said what type/layout of keyboard you're after. 60% keyboard parts are very common so it's easy to find a PCB, case, and all the other parts you'll need to build your keyboard. And all of these parts can come from different sources - with few exceptions they'll all work together. Other layouts can be difficult to find parts for, like a case for a 40%, a plate & case for a TKL or White Fox, etc. In these cases it's much easier to buy a kit (or join a group buy) which includes all the parts - when you can find one.
If you have the skills to craft your own case you have many more options. Some people have made them from wood, 3d printed, sandwiched plastic sheets, aluminum plates, etc. I don't have the skills or tools for such things but if you can do it you have many more options.
The bottom line is that for a first build a 60% is a great choice. You can choose your PCB (do you want fully backlit, or is that not important?), cases & plates are easy to find, you can mix & match PCB, plate, & case from different sources, and, in the end, a 60% is a nice size/layout which a lot of people prefer over any other keyboard size.
If you're not a member, join Massdrop. Keyboard kits come up for sale there quite frequently.
