For suggestions, we tend to try and keep sales within a 3 month period from today, so anything before that last august sale are not usable for a suggestion.

In terms of "how much are keys," we match the date of the sale to the average key price of that day on the platform. So we have the Aug 7th sale, with keys being priced at 1.75 USD at the day.

Lastly, there are more sales that happen outside of marketplace, and you'll need to find out what was traded (if you can find them at all)

Here This is the only one that has moved recently,

https://backpack.tf/item/8383029871

between the last two, being the Marketplace bot (MPTF) and the stn bot (Unusual #2), you are unlikely to find movement that you can track, but between the player "depression" and the stn bot will probably have movements that you can use for a suggestion.