Very large vase or nice container (Aston-on-Trent DE72)

Bit of an odd one. I'm looking for something to put my mum and dad's ashes into. I promised mum I would mix her with dad and make sure they stay together. The price of urns is ridiculous so I'm wondering if I could find some beautiful large container I can make into their final resting place together. I hope I don't upset anyone with this request but I'm struggling to find anything suitable in charity shops etc.