As long as you are in a good aquifer and the well isn't contaminated by surface water you likely won't *need* any filtration. Various types of filters may make the water more palatable and decrease solids though.

UV filters will help kill bacteria. 1000 seems steep. I put one in myself for peace of mind for a couple hundred bucks but it was several years ago.

If you have chronic bacteria issues after well treatment you probably have issues with your well.