You don't get any sort of deduction from your plan with Verizon for paying full price for a phone so it makes absolutely no sense to do that if you have an upgrade available or if you're signing a new contract.
If you're signing a new contract, you can get the Galaxy Nexus for $99.99 on Wirefly. If you're upgrading a line, it's $229.99 on Wirefly. Even on Verizon it's $299. ETF (early termination fee) starts at $350 and decreases by $10 every month.
So even if you bought it from Verizon for $299 and end your contract within the first month, the phone would cost you $649, which is what Verizon already charges off contract and the cheapest you can officially buy the Verizon Galaxy Nexus right now. If you end your contract after 6 months, the ETF is $290 and you got the phone for $589 instead of the full price of $649.
In other countries where your plan is cheaper when you bring your own phone, it makes more sense. In the US, there's no reason not to buy new phones on contract and have your carrier pay for most of the phone. I think T-Mobile is the only major carrier that actually offers a discount if you buy a phone full price.