Best bokeh under $500:
Sigma 50mm f/1.4 - has the smoothest, creamiest bokeh of any 50mm other than Leica Summilux / Noctilux, earning the Sigma the deserved nickname of "Sigmalux." This lens is high in the running for best bokeh period, regardless of price
Best bokeh under $1000
Canon 135L - really no contest here. It produces such unique and pleasing bokeh that it's one of the only lenses where I can look at a photo and know it was shot with the 135L.
Best bokeh under $2500
Canon 85L - if you want more bokeh than what the 85L can dish out, you have to step up to the 200mm f/2 ($6,000). www.howmuchblur.com
Finally - a complete and quality post not debating the definition of bokeh. Thank you!