Old thread I know, but I have an older model, the 379, and I believe it takes the same tips as the LF-389D. If it doesn't, the same sources definitely has tips for the LF-389D - in the US, Howard Electronic Instruments, which is where I bought my 379 some 7-8 years ago. I recently bought tips for mine, which are still available (as are heater elements), but I only wanted some in a different size, as the original one that came with it is still good.
I don;t know about dealers in other countries, but there definitely are a wide variety of tips available for the LF-389.