You just need to add your running cost for one year to the initial first cost of the plant and then divide by your sales(income) for one year . The result will be your pay back period in years.

Thanks Mr Kamal, I need specifc figure for 2T/hr sand reclamation plant Buy back period Roughly.1year or 2 Year

It all depends on what is available in the market and the price of each brand. Some companies offer good quality for a high price and some offer cheap prices for a poor quality product. Then you should look for what product is reliable and durable.