You can give a try to Balaton Volan (their contact). They have 4 examples of 260.43s still in service, however they will be withdrawn by the end of the year. Plate nrs are: ELN-921, EUE-613, GFX-945, GFX-946. (In local service there are still significant amount of exGDR buses, but there will be no new buses in that division in the near future, so those will remain in service for a while.)

These 4 vehicles had been given a complete renewal once in their lifetime. This meant full exterior and interior renewal. Their engine was swapped to a turbocharged Raba D10. They were well cared until about 5-7 years ago. Since then they are 'spare' buses, i.e. they replace other ones if those need some fix. This means their appearance is somewhat shabby.

If you seriously want to buy one, ask for all kind of pictures you can imagine. Their body structre may be rusted, which means that a decent amount of money need to be invested to achieve a presentable condition.

Try to contact them in German first. Lake Balaton (or 'Plattensee') is in the proximity, so there may be some person speak this language. Don't expect too much eager from them.

Other opprortunity is Bakony Volan (contact). There remained one 260.02 (DUL-848), which will go to the graveyard this year. Note that the third door was elaiminated on this vehicle. The information given above holds for this bus and company as well.

Good luck!