Oh, well... I'm afraid we would repeat some past discussion..
According to my understanding, the most notable different features of Jogja's and Solo's mendhak is their 'ungkat-ungkatan'. Solo's has a thin, skinny ungkat-ungkat, and Jogja's has a cone-shape ungkat-ungkat.
As a picture worth more than a thousand words, I attach some pictures which had been posted before, with some comments added. I apologize for 'copyright infringement', if any, and also to Mas Ganjawulung.
To Mas Ferry, you could find a fair/good new mendhak easily, usually the better one come in silver and yakut, but the old, good one (I mean, the better then the best new one could available), unfortunately, quite rare today.
Finding the right 'proportion' on ukiran (handle), mendhak, wrangka and pendhok is very tricky. Size, shapes, color, textures and balance/harmony have come into account. You must have several good stock of handles, mendhaks and pendhoks to make proper adjustment. And the utmost is, you must have 'the feeling' to judge the proper harmony. It is the most important part, and unfortunately, that money can't buy. It is also not easy to learn.