I add all coins up at greysheet and came up with 73.80. http://cgi.ebay.com/LOT-OF-20-1916-...mQQptZCoins_US_Individual?hash=item4a9f59e246
$73.80 is close enough to $75. Probably rounded to the nearest $5. So his wholesale value is essentially correct. Or the both of you used different editions of the greysheet. Prices change.
For any pricing guides I'm familiar with, the answer is "Yes". The only other way I know of to get wholesale prices is to look at auction results. But don't include eBay in that. And for those coins in those grades you are just not going to find auction results. So you're back to the greysheet.