Full hydro is expensive. The PSC kits are pretty competitive cost wise with the others I've seen.
If you want to go new and add up all the parts that come with the kit you'd be hard pressed to save any money by shopping around.
It can be done quite a bit cheaper by going used and hitting up Ebay for most things but I don't know of a "kit" that is much cheaper then the PSC stuff.
Even going used and running a single ended ram my full hydro was a little over $500 and i got a super deal on the orbital.