Iordered a bunch of spares from oomodel when Ibought my kit, mainly crash kit type stuff shafts and gears etc, but touch wood I havnt had to use any of that stuff yet
. The sleeve is the first part I've bought apart from some tail grip bearings both align from zeejays. Total cost about $10.
The small amount of slop that's been developing is from the bearngs in this part (pic below), which has the sleeve through it. When you consider I've done 150 plus flights and that part rotates at some crazy speed, I'm not surprised those bearings are worn out. This Align part is about $9 including the bearings or you can buy the bearings for about $4 and replace them in the plastic hub.
I did a lot of research on all these new fancy dual tail pitch slider setups and I can't justify the money. The align dual arm ones are like $40, and I've read reports from people that have upgraded that the slop returns after 20-30 flights so they are no better than the original.
If you get the tarot parts like the kit comes with, you can buy the whole hub bearngs and sleeve for about $4. I'm going to opt to spend $4 every 150 flights over any of these fancy new dual tail setups.
If your HK PRO is TT, I would just buy a whole tarot pro tail and then replace bits on that as it wears out.
The site you linked aust-rc-tech, I've purchased stuff from before. They include shipping on every item but will refund the shipping if you order multiple items.
Now that your skill level has incresed, you'll find that you don't crash as much and you can be more selective with your parts and what you have as you won't need to keep a bunch of spares all the time.