DIY aeration system, as not a dealer package item, does not have to be "a grand". Depending on the size of the pond it can be done well for $150-300 or even less if you use creative knowledgeable methods. One can copy concepts and items from package systems, but this takes time and homework to get your knowledge up to "par". Some find it easier to just spend the money rather than spend lots of time developing a good homemade aeration system. Numerous threads and posts in the Aeration Section discuss DIY aeration systems.
It will take time just sorting through the older appropriate posts.
http://forums.pondboss.com/ubbthreads.php?ubb=postlist&Board=11&page=1Gathering & locating parts can take time. Just learning the best or type of parts to use takes time. Time is money to some and plentifully cheap & available for others. Costs can be saved by using unweighted airline, building your own diffuser which takes time, and locating good used air compressors. Using unweighted airline can involves adding weights and then one has to worry about airline kinks and snags due to weights hanging on the airline. Good individual membrane diffusers are not real expensive and can be used separately or ganged together on a PVC manifold and are available relatively inexpensivly from various sellers.
I have seen creative guys with shallow ponds use the vacuum pump from a junk car for the air pump. Note car vacuum air pumps will only develop enough air pressure for I think 4-5 ft deep. Used air conditioner pumps can create air pressure. Most air compressor pumps have a vacuum side and pressure side. I saw one guy use a used cow milking machine for the air pump. Try to find something that is oilless. Getting the best one for the job takes know-how.
