Actually the Earlybird Kindergarten Math that we use is still available, as we carry it in our store here:
http://www.heartofdakota.com/singapore.php
It is an out-of-print item on the Singapore website, however if you do your shopping within HOD, then the Earlybird Kindergarten Math is available for use with our guides at this point in time.

As a huge benefit, it is very economical, with the workbooks only costing $13.50 each or $27.00 for the pair, but better yet it is an outstanding K math program when combined with all of the hands-on plans written to correspond with it in your HOD LHFHG guide.

It is our math of choice over all that is offered, and believe me we have tried most of them at one point or another!
The Primary Mathematics Series that we use is currently in print everywhere. We just have chosen not to update to the new Standards Edition of Singapore math for a few very specific reasons. Here are the reasons why:
viewtopic.php?f=6&t=727
As far as the Home Instructor's Guides go, here is a post explaining our thinking on that aspect:
viewtopic.php?f=6&t=4771
Here is portion of a past post in which I commented upon the Singapore HIG too:
While you can easily choose to use the Home Instructor's Guide, if desired, you may wish to give the HOD plans a try as written first as we don't see the need for the Home Instructor's Guides until level 5A/5B and 6A/6B, and then only as a reference. Your level of comfort may vary. The Home Instructor's Guides are actually written by Sonlight, so you aren't missing a part of the Singapore program or methodology by not using them. They are simply Sonlight's version of a teacher's helper and are not a part of the Singapore program itself. If you have questions about the Home Instructor's Guides, you may ask on Sonlight's forum. We also do not use the new Standards edition of Singapore math, so our plans are not compatible with that version. :wink:
After teaching many other math programs to my oldest and then using only Singapore for my next kiddos I can see a definite difference in my kiddo's math education and level of mathematical thinking and reasoning. However, it does take time to see the beauty of the Singapore methods.
Here is another portion of my past comments in regard to other components of Singapore:
The actual Singapore program does not require additional components to be added to it, as it works well as written. The extra practice books and Home Instructor's Guides are things that have been written by U.S. based companies to add-on to the Singapore program to make it more supersized friendly (like we like our math to be here in the U.S.) While you can easily add any of these components that you feel your kiddos need, we've enjoyed doing math purely the Singapore way and have found it to produce excellent mathematical reasoning and amazing mental computation ability.
Here is another past post about using the HIG with Singapore:
viewtopic.php?f=6&t=4896
So, while you can certainly add to Singapore, HOD's general advice would be to try it as it is first. Adding other components of Singapore is not recommended, but again, you certainly may do so if you so desire.
I hope that helps as you ponder math!
Blessings,
Carrie