Edit: btw, if someone at an HBS is unhelpful or condescending tell them that the the guys on the AHA forum think they're a bunch of douche-nozzles.
... and the gals think so too. I avoid one guy at the LHBS who was not only condescending (it was about my 20th AG batch and he was incredulous that I was brewing all-grain--excuse me?!) but spent the entire time complaining to someone else about his shift hours. I didn't weigh the grains when I got home, but I'm pretty sure he shorted me a pound or so of my base malt, simply because he was blathering too much. (Note: I now check my weights when I get home, and I watch the clerks like a hawk. A smiling hawk but a hawk all the same.)
Anyway, if the shop clerks were simply skeptical (versus outright rude) it could be that they were thinking what I was thinking, which is that it's not a bad idea if your first brews follow the KISS factor--they may actually be trying to ensure you're a repeat customer. Big brews are more expensive to make and it's also much harder to isolate what's going wrong. Kudos to you for your "go big or go home" approach, but at least for the next batch plus one, you might consider something very simple that will allow you to focus both on technique and on understanding and improving your equipment setup. Also consider small batches, which will give you room (financially but also literally--that beer that didn't turn out so great can take up a lot of space while you're waiting for it to turn into gold) to practice and experiment.