Home Improvement Store Kits -vs- Water Garden Specialist Kits

I am very very tempted to put a pond in my backyard for a variety of
reasons. As I have been looking around for kits for this project, I
have pretty much established that I want to go with a flexible liner
rather than a hard shell type pond. However, here is my concern:

You can go to Home Depot or a similar store and get a kit for a pretty
large pond for around $150, maybe $200 or a bit more, supposedly for
the whole deal to keep it clean and so on. Then, you look at
businesses and websites that specialize in this sort of thing, and
kits with pretty much the same stuff in it for a smaller sized pond
are many hundreds of dollars more. I remember years ago having an
above ground swimming pool that came with a pump that was a real
joke...it did not have close to a chance of keeping the pool
clean...will I run into the same problems if I go and buy that Home
Depot kit (Beckett or Little Giant brands)? Do these much cheaper
kits work okay? Or is it necessary to spend that sort of huge money
from a specialist to get something that actually works?

Any suggestions, sources, experiene with this sort of thing would be
greatly appreciated. Thank you!