It really depends on the fixture, but one alternative that I've used is Vista lighting. Specifically I've used Vistas version fo the Kim "square bullet" par-38 fixture.
There is practially no differnece, except for about $30 per fixture and the fact that, when you have ot replace a fixture in the future, Kim also has a three-unit-minimum on an order. This can be a real PITA when you only have to replace one or two fixtures.
Good Luck!