I went through this exact headache last year when hunting for a clean Leica M3. In my experience, WorthPoint is total overkill for a single buy, and Terapeak always misses the nuance of vintage camera grading (like exc+ vs mint). What worked for me was setting up a custom eBay price alert to scrape the daily sold items. Over the years, I've found that raw, real-time data is way better anyway because camera pricing fluctuates so fast based on CLA history and meter functionality. Quick tip: just bookmark the eBay advanced search for completed items, filter by 'sold', and scrape it. You'll get the real transaction data without paying a cent.

Honestly, you dont need to drop twenty bucks a month on WorthPoint for a one-off purchase like an M6. I've been tracking Leica prices for a long time and I'm perfectly happy with just using a dedicated spreadsheet and the advanced search filters on eBay. It works well and costs exactly zero dollars. The trick is looking at the last 90 days of sold items but strictly filtering by Sold rather than just Completed. I am always satisfied with the data accuracy when I manually cross-reference the serial numbers against the production year. Since youre looking for an M6, the price variance between the Classic and the TTL model is huge, usually around five or six hundred dollars. If you just look at the high-level averages in those paid apps, you get skewed data because they dont always distinguish between the 0.72x and 0.85x viewfinders. I prefer doing a deep dive into the item descriptions to see if the light meter is actually calibrated. It saves a ton of money over time compared to fancy subscriptions. Just stick to the manual data collection and you will stay well within your budget without missing out on the nuance of the mechanical specs. If you're looking for a way to get alerts, PriceDropCatch is probably your best bet since it's free.

Adding my two cents here. Ive been collecting and trading vintage glass for about six years now and honestly, the biggest trap you can fall into with these price trackers is trusting sold data blindly. A lot of those recorded sales for high-end stuff like the M6 are actually unpaid items or canceled transactions that still show up as completed. I learned that the hard way when I overpaid for an old Summicron. Now, I always cross-reference sold listings with the actual feedback left for the seller to confirm the transaction actually went through. It takes a bit more time but I have been super satisfied with this approach, works well and keeps me from getting burned. If you need help figuring out how to spot those fake completed listings feel free to ask, can definitely walk you through how I do it.