Hi eshek - and welcome!
If you want some prices, you'll need to give some more details such as how much stuff you have (in m3) and, perhaps, the weight.
Unfortunately, there are not as many transport companies working between Germany and BG as there are between the UK and BG. However, one company which travels via Germany when bringing stuff from the UK is called Gabieli - and you can find details here :- https://www.uktobg.com/home
If you have a lot of stuff, in my opinion a better option might be for you to hire a van and driver from Germany and travel down with them and your stuff.
That's what I did when I moved to BG from Northern Russia.