Converting headlights

Hello, I currently own a 1994 Pontiac Grand Prix 2 door SE. I have the type of headlights that you can't just buy the bulb, you have to buy the lens with it. The trouble is that it starts getting expensive to buy them every year for $30 each. I was wondering how hard it would be to just install lenses that don't need changed, just the bulb. If anyone has info or a web page telling how it is done could you please post it? Thanks.

I had a 93, never seen anything for that. sorry