Our friend Will Hart just sent me the following email:
I wasn’t sure if you saw the notice of this being posted on Ebay for $2500, so I thought I’d pass along the full-size jpg for your records.
Will
ps – Many Thanks to Charles Danny Lovecraft for the tip!
The letter is below; click to enlarge. View the eBay page here.

That’s interesting. This is the one that sold for just under US$900 on March 25. Someone is looking to turn a profit!
Transcripts of this letter and the other four letters from Lovecraft to Nelson are apparently available in the recent volume edited by Douglas A. Anderson, see:
http://www.nodensbooks.com/
Odd that HPL would type this letter, given how much he loathed typing. Just sayin’.