Went ahead and did the rest of the footwork to actually verify:

Sale 2, 5/01:

http://backpack.tf/profiles/76561198145465595#!/compare/1462060800/1462320000

(buyer, little more junk around it)

http://backpack.tf/profiles/76561198170706982#!/compare/1462060800/1462147200

(seller, easier)

With 5.5-10 keys of sweets (depending how you count parts)

Time Warp Lucky Shot (47.5, freshly updated)

Australium Rocket Launcher (55)

Australium Black Box (18)

5 keys

~2 keys sweets

= 127 - (5-10)

= ~120 keys

Sale 3, 4/22:

http://backpack.tf/profiles/76561198170706982#!/compare/1461283200/1461369600

(buyer)

Harvest Moon Grenadier's Softcap (67.5)

(Active suggestion not using this sale: http://backpack.tf/suggestion/5744cc0c83de6b3faa25c473 )

Australium Knife (22)

(Killstreak, but less than a key difference in listings for basic killstreaks)

Strange Professional Rocket Launcher (12)

(Sellers at 12, 12.5 and 13, buyers at 11.25 and 11.3, should be less than a key error.)

Maybe a key? Didn't register before going to bot if so.

= 101 keys

Sale 4, just to be thorough, 3/10 (basically outdated):

http://backpack.tf/profiles/76561198204701269#!/compare/1457337600/1457683200

GBH Dragonborn (~42, way out of date)

Ether Smokey Sombrero (~47, slightly out of date)

Professional Australium Knife (~35, market)

Headshot kills (2)

= ~126

120 (from suggestion), ~120, and 101. Supporting near-outdated sale at 126 suggests 101 is indeed an outlier given the following two sales. Oh, and the other one hasn't moved in over a year.

So... after all that, turns out 120 is probably fine.