JSFiddle - React, Tailwind, and code Playground

HTML

<select class="proso1" width="100%" id="proso_engine" name="enginephp">
<option value="0" title="" price-engine="0">по умолчанию</option> 
<option value="100" value-url="ссылка" title="" price-engine="100" product="engine №1">engine №1&nbsp;-&nbsp;100&nbsp;руб.</option> 
<option value="200" value-url="ссылка" title="" price-engine="200" product="engine №2">engine №2&nbsp;-&nbsp;200&nbsp;руб.</option>
</select>



<select class="proso1" width="100%" id="proso_table" name="tablephp"> 
<option value="0" title="" price-table="0">по умолчанию</option>  
<option value="10" value-url="ссылка" title="" price-table="10">table №1&nbsp;-&nbsp;10&nbsp;руб.</option> 
<option value="20" value-url="ссылка" title="" price-table="20">table №2&nbsp;-&nbsp;20&nbsp;руб.</option>
</select>

<div class="form_itog_01" id="result_02"></div>

JavaScript

var engine=document.getElementById('proso_engine'),
	table=document.getElementById('proso_table');
	
[engine,table].forEach(function(item){
	item.addEventListener('change',function(){
		var total=1000;
		
		total+=+table.options[table.selectedIndex].getAttribute('price-table');
		total+=+engine.options[engine.selectedIndex].getAttribute('price-engine');
		
		document.getElementById('result_02').innerHTML=total;
	},false);
});