This invoice, dated July 27th, 1973, is for 6.5 hours of recording time and a reel of 2" 24 track tape, which we still have in the archives. The grand total for the day's session was £277, or $700 at the then current exchange rate. Adjusting for inflation that would be £2,932 today, or $4,563.
This other invoice is for the three days prior. It adds up to £1,083 ($2,729) which is £11,458 in today's economy, or $17,831. Yikes!