no, you didn't do it wrong, you just missed some sales but they support your price, so no point in a resuggestion

sale 1)

https://marketplace.tf/items/30360;5;u84;strange

sold for $49.99 marketplace.tf

http://manicbot.me/keyprice/?at=2018-08-25 = keys were $1.90

49.99 / 1.90 = 26.31 keys = 26 keys

sale 2)

https://marketplace.tf/items/30360;5;u84;strange

sold for $89.99 marketplace.tf

http://manicbot.me/keyprice/?at=2018-09-16 = keys were $1.85

89.99 / 1.85 = 48.64 keys = 49 keys

26 key sale looks low with two other sales higher than it, also its the oldest sale by a month or so. I'd probably go with 50 flat here, no point in resuggesting to 49-50.

As mentioned above there's 2 other sales.

1 sale on marketplace at 26 keys. It went to a known quickbuyer and seems like an outlier here. Another sale at 49 keys on marketplace.

Now resuggesting at 49-50 seems rather pointless so I'll accept as close enough.