Lower chain tensioner is really easy on that motor, and if you want to do the vanos stage two rebuild (replaces sprockets upperr tensioner and vanos seals) there are a bunch of good DIY writeups online. Right after I bought my m3 the timing chains started to make alot of noise also. I did the lower chain tensioner and a vanos seal replacement, and it sounds like a new motor. If you are handy with a wrench, i would try to pick that up for about 1k. Good luck.
Member #2 of the Boston Green Mafia BMW-CCA #457574
1995 BG M3 2000 TiAg 4.4l X5
-I do the things today that others won't do, so I will have the things tomorrow that other won't have....