I use Amazon many times per year and I am a gold member at Monoprice. I hoe the two never combine in any way. Amazon's customer service, to put it kindly, is shit. Amazon's UI and order process is shit. I much prefer Monopice in these regards. Customer service is excellent there.

Amazon also treats its fulfillment employees worse than shit. Read the wonderful undercover stories. I've read two so far.

Super-saver shipping at Amazon takes longer than Monoprice's standard shipping. Yes, it's free. I'm surprised Monoproce's shipping isn't a bit cheaper - I'm sure it could be, but they're likely trying to make a bit there to offset their otherwise low prices on goods. I know what kind of pricing UPS offers to even marginally high-quantity shippers and the discounts are out of this world.

So, in summary, I'd like slightly lower shipping at Monoprice, and better web and customer service experience at Amazon.