I gather that after its chain of shops failed, Tandy reappeared as a legacy web-based operation.
They still exist -
https://www.tandyonline.com/
And will sell you a 12AX7/ECC83 valve for £9.99 or a 6L6 for £15.99 !!
I guess there may be a niche..... though I'll not be betting my pension on it.