Do you think that the buy back offer can be a good solution to improve sales and after sales offers??

Actually we are doing this operation a buy-back promotion and it is working fine.
As the purchasing power is decresing in some country, it is the perfect solution to get a new products with warranty and with discounts.
generaly refurbishing products or selling them as spare parts is beneficial

Good if the results of the study of the financial cost to re-manufacture the product and sell it as a hostile manufacturing is positive

Yes it is good for customer attractions and improvement of Sales and after sales Offer.
But it should not be without consideration of Marketing team and Finance team.