credible replacement part websites?

Let's talk about Apple first. Apple (the company) buys parts from a maker then forbids the maker from selling those parts to the world.

This means that spares are usually scavenged from donor boards. Sadly you used the word "credible" so I wonder if you meant "those that sell factory issued parts."

The answer to your question is therefore a solid [b]NO![/b]

So what are we to do if we need a part that the makers have worked to keep off the market?

1. Scavenge from dead phones, PCs etc. I use ebay for that.
2. For some Apple parts I turn to Louis Rossmann (google that name to find his YouTube channel and store.)

Now for PC parts, can you supply an example part you need? Sometimes folk want to repair a blown motherboard but unless it's a simple thing like a blown keyboard fuse or such, the motherboard is replaced.