Major thanks to AJ for correcting the pricing errors in my previous suggestion! Key prices are now as up to date as possible.

The prior 500 pure sale occurred on Jan 24th so is now outdated.

https://gladiator.tf/listings/6097db106f2b598155c1fd31 - buyout on the purchase was 600 keys

Key prices:

From the forums - https://forums.backpack.tf/forum/27-team-fortress-2-cash-trading/

Buyers:

https://forums.backpack.tf/topic/76754-wtb-keys-at-170-usd-each/

https://forums.backpack.tf/topic/38399-%F0%9F%94%A5buying-backpacksinventories-with-paypalkeys%F0%9F%94%A5%E2%80%8B-500-trust-ratings%E2%9C%85-active/

https://forums.backpack.tf/topic/66342-buying-keys-for-169-paypal-april-2021-%F0%9F%94%A5/

https://forums.backpack.tf/topic/76871-buying-keys-170-each-buying-special-keys-ref-tools-backpacks-paypal/

https://forums.backpack.tf/topic/38397-%F0%9F%94%A5frost-is-buying-keys-for-168-usd-paypal-500-trust-ratings%E2%9C%85-no-rep-needed/

https://forums.backpack.tf/topic/72542-sprekt-is-buying-keys169-and-backpacks-with/

https://forums.backpack.tf/topic/76862-buying-tf2-keys-with-paypal-for-170-usd-or-%E2%82%AC140-each/

https://forums.backpack.tf/topic/68510-buying-keys-for-170-backpacks-via-paypal-350-rep/

Most key buyers are at $1.70 on avg

Sellers:

https://forums.backpack.tf/topic/77688-selling-500-keys-for-175-paypal-venmo/

https://forums.backpack.tf/topic/76305-selling-mann-co-keys-174-each-paypalvenmozellecash-app-usa-based/

https://forums.backpack.tf/topic/75702-selling-900-keys-175-600-tour-of-duty-tickets-085-paypalzelle-keys-17-btc/

https://forums.backpack.tf/topic/77499-selling-keys-for-173-usd-paypalwise/

https://forums.backpack.tf/topic/78028-s-93-keys-for-175-each-paypal/

Most key sellers are at $1.75 on avg

Taking $1.75 as the value of PayPal keys currently

$1050 / $1.75 = 600 keys exactly

With this, sales are 500 (outdated) >> upgraded where it's valued at ~300 or so keys >> purchase of 600 keys PayPal

I think 600 flat works here based on all the above.

Additional screenshots for proof:

-paypal confirmation: https://i.imgur.com/j9ZUr0L.jpg

-trade offer: https://i.imgur.com/7EOZ8ia.png

-bp.tf inventory history: https://backpack.tf/profiles/76561197994342400#!/compare/1620432000/1620604800

have a great rest of the weekend!