For the TF10, if the other tips keep slipping out of the ear, try the SMALL Comply TX500 foam tips. Although not perfect for me, it is pretty close (and do not listen to those who say get the Sony tips, they are not foam and slip out also). I called Comply and told them my problem, and they were really cool (just a hint...). I ended up getting another pack of them (dad needed to fill up amazon.com free shipping order)....
So, I am really happy with the small foam (it is smaller than the ones that came with the TF10). Not a ten, but best I have used.
And I spoke to a friend who is an audiologist and a professor at a large university, and though it was 3 minutes on the elevator in passing, he told me that some ears are just shaped different and to think hard before spending the money on custom tips.
Also, I own the HF3 and though great isolation, the sound isn't as good imho as the TF10. Though, if you get the HF3 for 99$, it may be worth a try if sound isn't your only concern.
- MyTwoCents