Just enough to buy a decent house is well below the redar enough to not gain any unwanted attention.

Also, as long as it's not too flashy, you can probably get away with quite a lot.

A server rack can be places in the basement of your house, away from keen eyes. Compute further stuff there.
Get an old car in good condition. Get the AI to construct an AI driven control unit for the car (and spoofing any mechanic plugging in an OBD reader).
Under your house, dig an unusually deep well for efficient heating.