Dr. Prafull Das Gupta has given some good advice, especially about opting for full dental implant treatment rather than mixing dental implants with a partial denture. I’d definitely begin with getting some quotes from local implant dentists so you have a better indication of a reasonable price. However, the costs can vary according to the type of dental implant used, as some dentist will use generic implants that are less expensive, while others will use implants from one of the well-known implant companies. It will be easier to get components replaced if your dental implants are a well-known brand. You also mention you lost your teeth due to ill-health, so a good implant dentist should be able to tell you if this will affect treatment and if so the chances of success.