function money_focus(objid)
		{
			var obj=document.getElementById(objid)
			
			var v=obj.value
			var ec= 0 
			var ec_value = ""
			while(ec<v.length)
			{
				if(v.charAt(ec) >= '0' && v.charAt(ec) <='9') ec_value += v[ec]
				ec++
			}
			do
			obj.value = ec_value
		}
		function money_blur(objid)
		{
			var obj=document.getElementById(objid)
			var v=obj.value
			var ec= 0 
			var ec_value = ""
			var div = v %  3 
			if(div >  0 )
			{
				ec_value += v.substring( 0 ,div) + ","
			}
			while(ec+div+ 3  < v.length)
			{
				ec_value += v.substring(ec+div,ec+div+ 3 ) + ","
				ec = ec +  3 
			}do
			ec_value = ec_value.substring( 0 ,ec_value.length- 2 )
			obj.value = ec_value
		}

и это вызывается вот так
<asp:textbox onkeypress="onKeyPress_OnlyDigits()" onfocus="money_focus('TB_C_GrossSales')" onblur="money_blur('TB_C_GrossSales')" id="TB_C_GrossSales" бла бла бла></asp:textbox>