Some bottles may not need to be tumbled which Would consist of maybe running some copper shot with bar keepers friend or a similar method to get the dirt and muck out, however certain bottles that have been in the ground for long periods of time have what some call sickness. These bottles would need to be polished and when they are real bad they will need a cutter on them then polished.
The problem is some bottles are not worth the tumbling process. It will cost you 15 to 25 dollars maybe more to get them done and sometimes its better just to buy a nicer example down the road. Hope this helps.
I am at most an hour away from the southernmost end of Delaware. I will leave you a PM (private message) on this website with my contact info. I will be traveling through south Delaware, back and forth to Ocean City later this week, and maybe we can meet up then. Planning on being through there on Wednesday and Friday mornings.
Chris