Check out this page for pricing on one-off projects. The top row displays pricing for individual orders placed at the time of purchase. Volume discounts are available through the purchase of credit packs, as illustrated in the rest of the table.
Credits are like dollars, but discounted. So 1000 credits would be like $1000 that you can use on any of our products, but they are discounted 25% so you pay only $750 for them.