I think this very much depends on what you are wanting from your property or properties - you could build a fabulous house for 100,000E with pool etc. You could purchase a lot of smaller rural properties and either renovate and sell on or sit on them, you could purchase apartments and commerical property in cities such as Sofia, Plovdiv, Stara Zagora....
I think personally I would spread the investment around - maybe an apartment and shop or office in Sofia, a couple of smaller rural properties at the cheaper end (maybe to renovate and keep or sell on). Depending on if you intended to use property yourself you may want to buy or build nearer the coast or ski resorts...Or invest inland and just sit on it for a while.
Also depends what you call short and long term - 6 months or 5 years, 10 years or 20 years.....
Rachel