Pavers if made correctly are 10,000 psi concrete and less than 5% absorption so most of the stains will be surface stains. You could also try a low tech enviromentally friendly paste of baking soda. Let dry and brush off, repeat as necessary. This should greatly reduce the appearance of the stain.
Sealers will give the pavers a wet look and depending on traffic and climate may be renewed as often as every year so you can get a good revenue stream going there. Look for products like Weather-Bos for environmentally friendly sealers.
Cheers.