Depending on how much gold you have it is not necessarily as cost effective as you might think to re-use your metal as there are much higher production and consultation costs with this process. However if you are doing it for sentimental reasons it is a wonderful way of redeveloping an heirloom treasure.
To give you a very rough idea of cost, for design time and production of repurposing one piece without any stones, prices normally start around £1,500, depending on the complexity of the design. If stones are used there are of course additional analysing, customisation and setting costs.
It is definitely more cost effective should you have enough gold to make a larger piece, for example a structural ring, where the saving you make on the cost of gold really outweighs the production cost. It is also more cost effective if you are making more than one piece with your gold as the production cost reduces considerably for every extra piece that is cast. For example one stacking ring might cost £1500, two stacking rings would be around £2100 and £2750 for three stacking rings.