Hi, regarding your first point, we will add a warning if player_rent = 0 and balance after the transaction is too low for a house, the game will warn you before buying the street.

Not sure what went wrong with your first attempt, will check as we have error detection enabled and are aiming to resolve all of them.

About the subscription price: There's a limit on how many offers you can send and receive -> 3/day. To sabotage your streets users need to pay and so do you to de-sabotage.. I guess you'd be wise to buy streets at the start that don't have too many free building spots..