Trouble here is that it's an old farm place with tons of old metal junk in the ground. With aluminums it was no problem because I could discriminate out the iron and it would sing out near the alu shaft. With carbons, once they're under the grass, they're just plain gone. A metal detector set to accept steel/iron will beep about every three inches around here. Usually what you pay for with an expensive detector is the ability to discriminate coins out of aluminum and iron junk and extra depth, and neither of those is important for finding arrows. Some of those Chinese dectectors that copy the Tesoro circuits are pretty decent machines if you don't have a prob with the politics of buying Chinese stuff. Look for the cheap ones with the good reviews on Amazon.com.
Oh and there's the phenomenon of "iron masking" where a piece of brass or aluminum that's right next to iron will be masked out by the iron and won't show up if you have iron discriminated out. So even though you probably have aluminum or brass inserts in your carbons, they will still most likely show up as iron even on an expensive detector. Again, impossible to pick out of the ground junk around my property.