master lock force 6
 

nashbar has it for $16.something (regularly $70, i think), and i need a lock quick. worth it?

If your bike is worth $16.something i'd buy it. If you're looking at the same one i'm looking it, it looks like it has cylindrical keys.

cylindrical keys = bad?

...

yeah, i had an onguard and it was great. but i lost it, so i need a new one.

The reason they're so cheap is they can be compromised by (as stated above) a bic pen barrel.
A lock's construction is irrelevant when it can be defeated with an office supply.