Mobile phones are very tough market to be in - and buying them cheap to sell them for a healthy profit is even harder.
You will first of all need to decide where you will be selling them - if it's ebay, forget about it.
Wholesalers and international traders buy new models for 100's of pounds and sell them making a few pounds on each handset, and they sell 500 at a time to make a profit. - SO as you can see it is a tough market.
You have to be VAT registered to trade in mobile phones in the first place, making it even harder.
My advice, find a better product.