Disclaimer:
This is a just a guide, mainly for myself, if you lose money using this, it's not my problem.

Aquarium: 12k
Borak: 10k
Candytree: 4k
Computer Repairs: 2k
Cosmonaut: 3k
Desert Spy: 5k
Eleka Prison: 5k
Farm: 5k
Garage: 4k
Elger: 15k (with dcgb, 8k without)
Traveller: 7k
Leppy: 6k
Microwave: 3k
Santa Claws: 3k
Secret Santa: 5k
Excavator: 10k
Explorer: 10k
Stalker: 4k
Snowman: 4k
Travis: 5k