If you are an EU citizen you may buy property and associated land but not (because Bulgaria are ignoring their treaty obligations) agriculture or forestry land without owning a company. It is not even necessary to own a company to trade but you would be well advised to take professional advice on that.
Finding a suitable property is entirely possible without the help of estate agents but the process is time-consuming and can be frustrating. Use Google Translate to create search terms in Bulgarian and switch on automatic translate to see most web pages in English. If you do use an estate agent ALWAYS ask for written details of ALL the charges you are likely to incur. Agents here charge both the buyer and the seller commission of they can get away with it. I have written evidence of charges that run to several thousand lev for buying a modestly priced property. There are also services you will be offered which if you do the work yourself cost a few lev each but for which an agency will charge fifty lev for one, fifty lev for another and before you know it you have racked up a substantial bill.
Even looking at property with an estate agent can be costly. It may not look much at half a lev per kilometre but a couple of hundred kilometres is easy to rack up in a day. Then there are legal fees. I have a written quote from an English speaking solicitor in Sofia to handle all of the conveyancing work on a house at the other end of the country for 700 lev and if I can find a trustworthy local man to represent them at the Notary meeting they will reduce it to 400. An agent generously offered to arrange for a local man to do the same work at an all in fee of 1000 lev. Bear in mind that none of these prices included disbursements.
Beware also the highly recommended local man who knows the ropes but has no formal legal qualification. There is one of these in our area and he will do everything for you which a solicitor (who is subject to professional rules) would do for only 500 Euro. Mayors here are public officials not politicians and they are there to work for the benefit of their villages. Generally, they are helpful and very knowledgeable about what is going on in their area. They may even make a few introductions but remember that most of them will not speak English.
We had optimistically allowed six months to find a property and move in despite tales that a couple of years is a more realistic time frame. While I'm not convinced yet that the latter is necessarily always the case I am convinced that six months is not enough time to devote to learning how things work, identifying where you want to live, finding a property and moving in. Adding the layer of discovering how to do business here and where best to base it you need to be certain you have adequate time and funds before moving to Bulgaria. Do that and it is entirely possible to do it yourself without courting disaster.