Buying a replacement screen

[alternate_UK]

Need to buy a replacement for a broken screen. No problem getting the old one out and the new one in, but buying one seems a bit perplexing.

All the people who supply spares on ebay and their own websites just want you to give them your existing part number and then they give you a price for a replacement compatible model that may say LG, Philips, etc but they are all "part sent may be form a different manufacturer - which ever we have in stock". so it isn't like you can look up the parts and maybe pay extra for a better screen or specific manufacturer.

Anyone have experience of this?

thanks