I'm a landlord. If you could afford to pay 6 months up front, I'd insist that you use a month's worth for the deposit. (In fact, I'd insist on a deposit in any case.)
You say "a lock in price." Do you mean for a rental or for a lease-option? For a rental...sure, within reason. And that's usually the way it is (and should be) done for a lease-option.
Reduced rent? Probably not. Over what period of time?
You're assuming, I think, that paying 6 months at a time gives the owner some great advantage. It really doesn't. Example: Let's say your rent is $2,000 a month. Interest rates are close to zero. But, just so we can work with a number, let's say 5%. You pay 6 months in advance. A normal rental pays one month in advance. So you're giving the owner an additional $10,000. What's the interest on that? 5 months of interest on the farthest-out payment and 1 month of interest on the closest one. That's roughly $600--or about $100 a month in interest (if I could get a 5% return). Let's say I split that with you. That'd save you $50 on a $2,000 a month lease. I doubt that's what you had in mind.
I certainly wouldn't do any of that without a deposit.
Hope that helps.