It's a lot easier to buy an SDR than a SAM -- even ignoring the cost differential.
Building an SDR which can output a signal strong enough to overpower the ILS array is not going to be cheap, subtle, or particularly easy. ILS is glitchy and pilots are trained to deal with the glitches — a localizer can be disrupted merely by having a plane (or any other large metal object) nearby.
Building an SDR which can output a signal strong enough to overpower the ILS array is not going to be cheap, subtle, or particularly easy. ILS is glitchy and pilots are trained to deal with the glitches — a localizer can be disrupted merely by having a plane (or any other large metal object) nearby.