Since each projector and monitor are different, prices and designs will differ. I will try to make the instructions as general as possible. I used an old Hitachi monitor and a Apollo Horizon Ultra overhead. I managed to get everything for free, and the same could apply to you! This project could take anywhere to a few hours to an afternoon depending on your specific situation and how much time you put into your fixture. The required skill varies from very little to experienced with electronics depending on if you can have the original power supply to the monitor and if the cooling fan needs to be soldered to a power supply.
Just keep in mind that the projector will be far from HD, but its a fun project and most people will find that the benefits outweigh the costs.