Craig -
Mackenzie's Golf Architecture published in 1920 is worth over $1,000. Three times that if signed.
Joyce Wethered and Tom Simpson. The Architectural Side of Golf published in 1929, $2,000 to $3,000. Or $15,000 if you can get one of the limited edition of 50 that was produced.
H.S. Colt and C.H. Alison. Some Essays on Golf Course Architecture published in 1920 $1,200 to $1,500. Double the price if you find a copy with a dust jacket.
Working looking for at bargain bins, no doubt. You never know.
Joe