My votes:
various Buck knives, probably more good knives in that range than any other company
A few of the AG Russell models, the Hunters Scalpel and Woodswalker for instance.
Opinel, of course. You can buy a set of ten for $60.
CRKT has many high-style designs that would otherwise be unaffordable to most buyers.
SAKs, if you like them.
Schrade Old Timers, many models can be bought on the secondary markets for under $30.
Vintage Bruckmann knives. Common on eBay, often for $30 or less. Very good quality, and a true bargain price for pre-WWII German craftsmanship.
And most importantly, if you are patient and bargain-shop there are some incredible blades for $30 closeout. Two of mine that were $30, an Effingham Ek Bowie and a 6" Camillus CUDA CQB.
-Bob