to expose digital photos you could use a video-projector.

The process, all in all, is quite an effort, and time consuming. Basically you can use liquid emulsion like liquid light, or one from rollei. You warm that emulsion to 40° in a water bath, and then you coat the wall (all in red light). Don't paint it on like you would do with colour, but apply quite a thick layer.

Then it should dry for 24h in total darkness. My dark-tents are never dark enough though, so I give it one night (have to get up early). Don't forget to also coat some small pieces for your probes (exposure time).

Once this has been achieved, you use pump-n-spray bottles to develop, fix and rinse it. I put trays and foil underneath the picture to collect the waste chemistry.

Aftrewards, once it is thorougly dry, you can coat it with varnish.

For the costs I'd check at a shop like nordfoto.

Where in Bulgaria are you planning to do it? I had one up close to Pavlikeni, but it came down during the winter.

Hope that helps.