[рони]

AlexFoxx,

var ser = document.querySelector('[name="services"]'),
       vol = document.querySelector('[name="vol"]'),
       sum = {
           "copywriting": 350,
           "selltext": 600,
           "hometext": 550,
	   "abouttext": 500,
	   "formedia": 450,
	   "pressrel": 400,
	   "goods": 200,
	   "rewriting": 200,
	   "commercial": 500,
	   "comments": 80,
	   "context": 100,
	   "blogs": 350,
	   "mailing": 350,
	   "news": 350,
	   "present": 750,
	   "poetry": 200,
	   "prose": 250,
	   "editing": 150,
	   "correction": 100
	     };
   ser.onchange = vol.oninput = function calc () {
   var price = 0, text = +vol.value || 0;
       price = (text * (sum[ser.value] || 0)/1000);
       if (text > 99999) price *= 0.85;
       else if (text > 49999) price *= 0.9;
result.innerHTML = price;
   }