Left Lane Sports has Mens Columbia Bug Shield Pants on sale for $32.45 + shipping. Two color options, all sizes in 32" inseam. Seems like a good deal, a google search yielded nothing below the $75 MSRP elsewhere. I assume they're similar to the exOfficio InsectShield line.
My invite link is below, you will receive a $10 credit towards a $50 purchase for signing up via the invite. Let it be known that I also receive a $10 credit if you make a $50 purchase. You can also sign up via their site directly (but don't get the $10 credit). With the credit it, buying two pairs comes to $54.90 plus shipping, cheaper than buy one get one free at the MSRP.