[BROO]

You can pick those lenses up dirt cheap. It is a good one to DIY because it is relatively simple. Also it is quite a good sharp lens with smooth bokeh....If you are in any way mechanically minded then you won't go wrong.
Check the lens reviews too. There is a diagram for reference.

[someasiancameraguy]

If its a really small patch of fungus and you dont want to mess with it, just leave it under bright sunlight for a few days and it will slow the growth. Other suggestions here are also good if you want to fully repair the lens.

[SamirShah]

I've purchased dozens and dozens of lenses "for parts". Most I thought I might be able to successfully repair/clean. From my experience, I've found that you never know for sure going in to most lens repairs if you can clean / repair the lens or not.

For example, I've been fooled more than once by haze and fungus thinking that it would be an easy repair job. But once inside, I determined that none of my 6 or 8 solvents would effectively remove the haze or fungus residue. Also, it's easy to mis-diagnose a problem. On occasion before taking a lens apart, I iniitially thought the problem was fungus or haze and once inside found that it was really "separation" (a fatal and non-repairable problem).

But, we've all got to start somewhere. So, if you can afford to trash this lens you're having problems with, I encourage you to watch a few YouTube videos on lens repair, buy a few rudiementary lens repair tools, and have a go at it. Your success rate will go up in time, but even after doing it for over 10 years, I still end up trashing a lens every so often because I was unable to repair/clean it.

Good luck and have fun!

@Fenwoodian - do you still have the project lenses with the separation haze issue? I'm about to tackle fixing this on my M-100f4 macro, but should really practice first on a no-downside lens. Thanks, Samir.