You want cheap? Stuff your mixes through a (k)racked Maximizer plug-in. If you don't have that, I have seen ads online for Mastering $15/hour. That is what they use. It will be louder.
You want good, save your extra pennies and send it to someone who really knows what they are doing.
I was at a mastering session yesterday, just about $200/hour. Worth every penny.
"An intellectual says a simple thing in a hard way. An artist says a hard thing in a simple way." - C. Bukowski