[RKDinOKC]

This one is made by 1byone. It has a battery operated button and either a battery operated or plug-in receiver for $12. It has 3 volume levels and 36 chimes. And has a modes to just flash an LED, chime, or both. You can add as many receivers or buttons as you want for $9 each. Each button can be programed to make a different chime sound. The lowest volume setting is supposed to be 25 db and the highest 110 db on the plug-in receiver, says >85 for the battery powered receiver. It is the only doorbell that listed an actual db level for the sound.

Since I don't have many electrical outlets I got the button and battery powered receiver and an extra battery powered receiver. Since my existing doorbell is wired and has a wired button I am thinking I can open up the button/transmitter and connect the wires from my existing doorbell button so I don't have the funky looking button thing outside.

There was one designed by some fancy smancy designer (looks like a bang and olfsen) that has a bunch of tones or you can record your own. It was $149.

There were also several from Honeywell that has from one to 50 tones that you could use different transmitters and/or contacts like triggers for doors and windows or fire alarms to make different tones as well. They started at $49 and went up to like $99.