Had I caught this thread originally, I would have said zero.
Since then, I have obtained 6x7, 6x9, 4x5 and 5x7 enlargers. Total price paid, $40. I gave the 6x7 and the 4x5 to others.
I did replace the lenses in the 6x9--50mm EL Nikkor f2.8 for $22, and a Schneider Companon 105mm for $20. Plus a glass 6x9 carrier, $40, and a bunch of glassless carriers of various sizes for about another $20 total. So, I have more money in lenses and carriers than in the enlargers.