I'm glad to be using Gladiator.tf Stats for this suggestion

Using all Killstreak tiers except for Professional because they sell for a lot more

Rounding everything to the nearest key since it's worth over 30 keys

Non-KS sales: https://imgur.com/45JODVd

Sales:

1 @ 38 keys 44.77 ref ~39 keys

1 @ 38 keys 44.44 ref ~39 keys

1 @ 41 keys

1 @ 40 keys

Buys:

1 @ 35 keys 40.66 ref ~36 keys

1 @ 36 keys 30 ref ~37 keys

1 @ 39 keys 25.55 ref ~40 keys

4 @ 39 keys 26.44 ref ~40 keys

1 @ 39 keys 26.22 ref ~40 keys

Basic KS: https://imgur.com/3y1VR5C

Sales:

1 @ 40 keys

Buys:

1 @ 33 keys 35.33 ref ~34 keys

1 @ 34 keys 6 ref ~34 keys

Specialized KS: https://imgur.com/rKqdXzv

Sales:

1 @ 36 keys 29.77 ref ~37 keys

1 @ 42 keys 36.55 ref ~43 keys

1 @ 41 keys

1 @ 40 keys

1 @ 37 keys

1 @ 36 keys 30 ref ~37 keys

Buys:

1 @ 35 keys 48 ref ~36 keys

1 @ 36 keys 19.11 ref ~36 keys

1 @ 36 keys 40 ref ~37 keys

Classies:

(Non KS) https://imgur.com/jcvgsMj

(Basic KS) https://imgur.com/qqPuYGu

(Spec KS) https://imgur.com/2sAv2Gk

Lots of buyers at a little over 37 keys on the non KS version, Anything under 37 is going to be low but gonna include 37 because it's a fairly common trading point

3 sellers at 40 keys on the Specialized Killstreak version, one has been there for 4 days and an other has parts, 41 and 43 will be a bit high but 40 is a common trading point

Let's go 37-40