I imagine you have quite a large roofing job for there to be a difference of £1000.00 between 2 Quotations. I do succeed in winning all of the quotations I submit, mainly reflected on the customers perception of the price. I like to think I charge a decent labour rate, have combined liabilty insurance to pay, which is also covering the customer, also unforseen overheads, such asI pension, accountancy charges, administration and the costs associated with purchasing the leads, time and travel to visit and quote the jobs, and if unsuccessful, the costs we have to try and recover. I would recommend receiving 2 or 3 quotations, scrutinise them carefully, for specifications and guarantee, and also check the references. We have first hand experience of people spending their hard earned money, then employing unscrupulous contractors to carry out work at over inflated prices, and carrying out terrible workmanship. Hope this helps, if I can be of further assistance, please do not hesitate to get in touch.