If you think you’re able to put a rig together, I would recommend building it yourself.
This is the guide I used, and for the first rig I built, it worked great:
Once I had all of the parts, I had it up and running in under an hour. But I have experience working with that kind of hardware and what software to use (claymore’s version 9.1). You’ll have to find a mining pool and edit claymore’s start.bat file - the readme explains how to do that.
So I decided to build another identical rig, but have been getting bad equipment, so it is taking me weeks to get it set up.
I don’t know of any good source to buy a pre-made rig. If you can find one on ebay from a highly rated seller, you can return it if it doesn’t work. You may be getting equipment that is near the end of it’s life span though, and paying twice as much as you’d pay if you built it yourself…