Spent some time solo in Bosnia back in September and ended up having a perfect trip. I cannot recommend it enough! Most underrated country in Europe without a doubt.
I stayed in Mostar (Majdas Hostel) for two days. It was amazing and the hosts were offering a very unique tour through the country side of Mostar. The Old Town was incredible. I then took a train to Konjic where I stayed for two days. Very underrated city for hikes and overall slow life. Finished in Sarajevo for 3 days... Such a unique and beautiful city.
Bosnia is not expensive at all! But it doesn't get a little more expensive in Mostar and Sarajevo. A lot of Canadians and Australians visit Bosnia because they don't use Euro :)
Bosnia is very safe. As a solo traveller I didn’t feel unsafe once. And people are so hospitable!
May/June is an incredible time to visit! Not too crowded and enjoyable weather.
Please let me know if you have ever been, and don't hesitate if you have any questions!