JD there are a number of decent knives that will fall into your budget range and I think it is an excellent idea(puma, gerber, buck, schrade, case, etc).
Others could be a leatherman multitool, stainless steel thermos, wildlife art with engraved plate(print, duck carving, etc), compass (SS ones can be engraved) or even a lansky sharpening kit with engraved plat stuck on the case.
Remember they don't have to be the exact same item if you want to tailor it to the guy. For my groomsmen they got different items that were personalized to their interests but cost me the same money.(It worked out very nicely)
Best of luck in finding the right gift and with marriage