I am no expert, but the things I would worry about: - cost to get into geostationary orbit might dominate the value/saving of the cheap instrument, so it might

I am no expert, but the things I would worry about: - cost to get into geostationary orbit might dominate the value/saving of the cheap instrument, so it might be smart to spend more on that - managing and controlling it might be very challenging - need to get the data down from it - might create difficulties and costs that kill the value - heating and cooling in space might kill it - radiation in space might kill the hardware - acceleration during launch might kill the hardware - the payload needs to be stable during launch or there will be an accident - scientific value might be lower than other missions for similar spend