I have both the DC30 and the DC40 collars for my Astro. I used the DC40 for the first time this past week and can't say I'm sold on it being better than the DC30. It tends to drop communication more frequently and it goes through its charge more quickly. It also doesn't like to connect to the 220 as quickly as a DC30. You might think about a DC30 instead. I don't have any leads on where you can get them, other than the usual online sources like Lion Country Supply or Dogs Unlimited.