go with a kit if its your first pond.remember Bigger is Better!most people redo the pond after the first year saying "its just not big enough". if you have the room go with at least 1500 gal. that will give you 1 or 2 koi and 5 comets.the signature series is the best ive worked with. http://www.aquascapedesigns.com/products/items.php?catid=36
it might cost a few dollars more but well worth it. good luck steve
Mushroomman i beg to differ.that aquascape system is the best, the pumps are all 2'' and 3000/gph or better.the biofalls are round and easy to hide with the insert tray.the skimmer box even comes with an adjustable faceplate. thats big if you dont have a transit for larger ponds.even the check valves are 2".
i install at least 4 of that kit a year with no complaints.
we just got liner and some rocks to hold it in place then some gravel on the bottom, found a pond pump and a few plants and added fish that was about it. land scaped it and made a water fall thing.