These amounts are what the game charges you for the upgrades. You need to have significantly more money than this to be offered the upgrade. The game will not leave you with less than 5,000G.

First stable upgrade unlocks some monster types, second stable upgrade triggers the UFO visitation. The House upgrades add slots to your item inventory.

You do need to be on the Ranch on week 4 of May, for the event to take place. Make sure to have lost of cash and be present at least one week prior to the event to trigger it.