I'm curious to see how this works out, as I've never tried to negotiate online before - only in person. Some times I just ask "what can we do to lower the price." For something like a laptop, you might lower the price by committing to it, i.e. agreeing to "no return" for the lower price. This takes some risk off the table for the seller, and I've had good success with it.
When dealing in person, offering cash-in-hand is also a powerful negotiating tool.