Serial stacking Linear regulars to increase Vin range
You could use a transistor zener regulator to drop most of the voltage, and put it in series with a linear regulator.  A basic transistor zener regulator looks like this:







simulate this circuit &ndash; Schematic created using CircuitLab

The output voltage is set by the zener. Q1 must be rated for the full Vin voltage, and for dissipating a power of Vin * Imax, so it may need a heatsink. R1 is chosen by trading off the current and heating at high Vin against having sufficient current for effective regulation at low Vin. For a negative regulator, turn the zener around and swap the transistor for a PNP.

The design can be improved in several ways, such as by adding a capacitor in parallel with the diode to give better regulation at higher frequencies. Or using a MOSFET for larger currents and/or lower dropout voltage. Ultimately, this kind of circuit is not going to be as good at regulating as a linear regulator, but that doesn't matter if you have a regulator too. And it's pretty cheap.