I don't know of a cheaper direct replacement. But you might be able to design a similar driver employing an NPN-PNP totem-pole, provided you don't need isolation. I've seen quite a few PIC based sine wave inverters (mostly 16F72) that employ TLP250. If your circuit is something similar, you won't need isolation especially since the MOSFET and the microcontroller share the same ground anyways.
However, may I ask, how expensive is the TLP250? The price here seems rather reasonable and cost isn't usually too big a factor when it comes to sine wave inverters.