I have had good success with several Nikon ProStaff scopes. I like the 2-7x32mm "Shotgun Scope" on my in-lines. I bought a 3-9x32mm from Cabela's Bargain Cave for under $100 and it has worked fine for several years now.

I also have bought the $30 Tasco from Walmart and it has been a solid performer on a Huntsman that I have.