1. TFC; 500$ (Rarity: Legendary + custom voicelines/SFX)

2. Zombified; 666$ (Rarity: Legendary + custom voicelines)

3. Bloxxy CEO; 750$ (Rarity: Legendary + custom constructions, custom voicelines/SFX)

4. '08 Builderman; 1000$ (Rarity: Ancient + custom constructions, custom voicelines/SFX)

TFC (Fred Conagher) is an original Team Fortress Engineer who's canonically Dell's (TF2 Engineer) father.

Zombified comes from the Halloween events bundle appearing also as the enemy in special MVM map.

Bloxxy CEO, as you guess, is Builderman (David Baszucki) (I felt annoyed placing him there)

'08 Builderman - Ditto, but more rethro. (and swaggy)