New Toyo 8x10 holders go for $200+. LF is not for the faint of wallet. The only way to justify these items as new is that they are (hopefully) a one-off lifetime purchase, to be reused again and again, then eventually resold as used at your estate sale. If one has not yet reached that level of LF commitment, then used holders are the way to go.
Since no seller intentionally advertises leaking used holders, find an auction that allows a 14-day return. Buy some holders. Place a sheet of 4x5 b&w photo paper into each holder. Set them out in the light, over easy, like the eggs. Then process the paper and return any that leaked. No one can contest a returned leaking holder, unless the auction description originally stated they were leaking. Which of course it didn't.