I would like to recommend the Crystal Land Factory Shop in Sunny Beach, the quality of the glassware in there is superb.
When we first visited Bulgaria there were two shops in Old Nesebur, then due to circumstances these were closed.
They then re-opened a couple of years later in the Hotel Helios, and closed again.
Now a new shop has opened in Sunny Beach on the main road near to the centre, it is on the same side as the market.
If you visit my website I have posted some pictures of the glass, and written a blog, I have only seen it for sale in England in a couple of places, and the prices were at the high end, so if you purchase in Sunny Beach you will definitely obtain a bargain
Cheers
Ted the Red