You should be able to buy just the glass with the blue dot. That shouldnt be too bad. I just replaced a broken glass lense with blue dot in my 47 ford, and it ran me around $15. The whole assemble is pricey, but you should be able to find a blue dot glass lense for under $20. The time you will spend grinding a hole, and keeping it perfectly centered, and not chip the glass edge will be rough.