cheaperthandirt.com. They usually have some pretty good deals oon scopes there. You can get a decent 3-9x40 for under $150.00. I would not go with the fixed power unless it is a handgun scope. The variable power scopes are alot nicer to sight in on the range and give you alot more versatility in the field as well.
I just looked on e-bay and there are some deals to be had on Nikon Prostaff scopes. 3-9x40 NIB for about $130 is a good price. I always suggest Leupold's for a scope because it is a lifetime investment and the rifle is no good if the scope is junk, although I have gotten some good service out of some lower class of scope - I am a fan of the Bushnell Trophy line and own a couple of them - last time I checked they were about $80 to $100. Bushnell is a brand other than Leupold and Nikon that I would trust.