Anyone know where I could get a half cab conversion for my 84 Chevy blazer for a reasonable price or any ideas how to make one

 

Finding one of the aftermarket ones for a reasonable price would be nigh impossible. They were rare back when they were produced and I do not believe that anyone is actively making them anymore other than paying through the nose for a one off.

If you have a spare top, the link below (pdf attached as well) is a how-to on making your own. It does require welding.

Project 62, Converting the M-1009 Blazer to Cab and Cargo Box Style