The same process of import in BG is the same as any other EU country.
We import dive gear into the UK from Taiwan and some finds its way here, the easiest thing is to have it imported here depending on cost.
Some carriers do not come to BG and the delivery is costly, using a second carrier.
For delivering into the EU you need a pseudo turn number thats if you are not VAT reg.
Then you will need a forwarding agent who deal with the release of the cargo from the customs and deal with taxes and basically everything.
The forwarding agency will need all the documentation on the goods and the proforma invoice.
If you do this in the UK and bring them on into BG you will need a bonded ware house and declare and deduct taxes as you leave the UK and enter BG.