Got quoted for a timing chain and now I'm scared to approve it

[phineasfogg]

My A4 started making this faint rattling noise on cold starts a few weeks back and I finally got it looked at, the guy said it's the timing chain and gave me a quote that I've been staring at for two days now. I trust the diagnosis but the number is big enough that I want a second opinion before I hand over the car, especially since I've read these can sometimes be something simpler like a tensioner. A mate sent me https://audi-repair.ae saying they do this kind of job regularly and would tell me straight whether it's really the chain or not, but I wanted to ask here first if anyone's had timing chain work done on an Audi and whether the price varied a lot between garages. Also slightly worried that if I keep driving it while I decide, I might turn an expensive job into a catastrophic one.