Darren,
There are many of this type of parting tool on the market, Glanze do come out about the best. But as you said, the tips are rather expensive.
Remember me saying about the correct grade of tip for the job, well the one you have just made, is not, most probably, the correct material for the stresses of parting off, hence it keeps chipping.
That is why the tips are most probably so expensive, horses for courses.
Also each manufacturer of holders tends to go for their own particular shape of tip, so making the choice even more like a minefield. They only have to come up with a new shape, and it means starting over again.
I bought one from Chester UK many years ago, and bought 5 tips with it, luckily they are a type I can regrind myself, I am just down to the last tip, so in another year or so, I will have to find another one that works as well as this one does.
That reminds me, I must contact Gareth at Chester UK, to check to see if he has any old stock stashed away somewhere.
John