I can appreciate your concerns.
Even though the economy is bad, it has had no affect on material costs. In fact, costs for most items involved in pond construction (pump, skimmer, filters etc.) have risen this past year.
Additionally, the excavation stage of a pond of any type is the easiest part of the total process. Anybody can dig a hole. What is done with that hole to create a properly functioning healthy environment for aquatic life requires a goodly amount of knowledge AND experience. This is, along with material costs, what you are ultimately paying for.
"Everybody is ignorant, only on different subjects." - Will Rogers