TLDR - there's essentially 2 ways to go:
- Single adapter. Card is inexpensive, and reasonable 1TB SSDs start a little over $100. Expect R/W speeds above 1350 MB/s. For example, I have a Riitop adapter and HP EX920.
- Switched adapter. Costs more, allows more SSDs. Greater performance. If you need this kind of performance, best to read the sticky.
Common disappointment: "Doesn't boot faster!" That's right.