You might consider a second hand system, the ladies next door got one and still get it serviced if there is a problem. I am not sure of the cost but there was a saving. They don't appear to have much trouble with it apart from the sedate rate of traversion.
A relative who has recently died had one for the last year of his life.
I will try and enquire how much it cost. I do know it was rented and not purchased outright. When the time came to take it out, the firm couldn't come for a few weeks and rent had to be paid on the empty flat until it was removed.
Have you tried your local council? They will have had lots of experience of making adaptations to homes and may be willing to offer some guidance. In addition, depending on your individual circumstances, there maybe a grant available to part fund the cost. Again, your local council should be able to advise.
Social Services at your local council can advise and install a number of devices to make life easier.
However, they work within budgets and even after a home visit assessment you can wait years for any action. My relative needed some of these things 5 years ago to make life easier, like a bath lift and door entry system yet some were only installed in the last few months of his life and will now have to be removed again at further cost.
This doesn't include the stair lift which was financed privately as there was no realistic chance of getting it through Social Services in a reasonable time frame.
You should claim either "disability living allowance" if you are under 65 or "attendance allowance" over 65. Telephone 0800 882200 and they should tell you, in fact give you excellent advice. Once you have this there should be very little if anything to pay. Hope this helps.