"If you are pricing this like a business, you have to anticipate what competitors will do. "
Yup, and they'll do about the same thing, unless they don't know what they're doing ;)
A few things to consider as well. When somebody (the customer) does a lease on something like this, they're not just trying to get a payment plan on equipment, they're offlaying the risk and hassle of dealing with a component outside of their core competency. Although it wasn't explicitly stated, when the OP describes a lease scenario, I'm assuming they also mean the other risks that are associated with that. The customer is going to expect the equipment to be 100% operational and have any incidental outages fixed most likely within 24 hours. Damage from something like a backhoe hitting a camera wouldn't be covered, but if something fails due to jobsite issues like dust, vibration, bad power, etc., that should be covered as part of the equipment lease. All those things are factored into the price, and there is a moderate probably that during those 4 months SOMETHING will break.
I know of several integrators that are doing similar forms of equipment lease/rental. The going rate is closer to 1/6 - 1/8 of total equipment cost per month, but some of them also have minimums.
The equipment here would have an expected lifespan of about 14 months. Lease rates are based on street price of equipment divided by 6 or 8, but after about 30 days it loses a big chunk of value. So, a 4 month lease is going to have a premium attached to it. Theoretically the customer could rent the equipment for 6 or 7 months for the same out of pocket cost, but the integrator needs to make sure his business is covered first. If he loses the deal to someone who isn't aware of all the surrounding factors and underbids, well that happens all the time...
The $1 buyout lease is also common in cases like this. Where, if the end user really wants the equipment, the contract is structured so they have the option to buy it all for $1 at the end of the lease term.
There are lots of similar examples... leasing/renting electronic equipment is not cheap and I haven't seen any company become viable renting things for what you would at first consider "affordable". When I was in a different business, we rented A/V test and certification equipment to guys doing home theater installs. Stuff like spectrum analyzers and color-calibration equipment for TVs. It was priced at (Equipment Purchase Price/30) as the daily rental rate. Meaning that after one month of rental the equipment was paid for. I had several guys that over the course of a year bought an audio spectrum analyzer 4 times over in rental fees. Of course, they only rented it when they needed it, they baked that into THEIR prices to the THEIR end-user, and when a piece of equipment got lost or damaged by UPS, or suddenly died on-site, I had to expedite a new one out to them. So, that "paid for in one month" math didn't always mean we were rolling in dough, but it worked out that we made money overall, and the dealers renting the equipment didn't invest in expensive gear that could be a bit tempermental at the most inconvienient times.
When I rent A/V equipment now for trade-shows, it's about the same math still. For what I pay for 5 days rental of a "good" 42" display I can go to Wal-Mart and buy a decent consumer unit for about 10% less. That works great, until the Wal-Mart display dies halfway into the second day of your trade show. When that happens, I need to go source another unit and deal with swapping it out. When the rental unit dies, I call the company and two guys are there in an hour with a replacement. Both options have pros and cons.
Lastly, OP didn't ask "I'm starting an equipment leasing business, what's the going rate for X". If he had, I would have probably said (Equipment Cost/8) as a good rule of thumb for pricing. The price for a 4-month lease is going to have a premium, and because he most likely does not have more business lined up behind this to redeploy the equipment on, the value *to him* for the equipment at the end of the term is effectively $0. He's trying to make money, not run a rental charity.
I've also known a couple of integrators that tried to get into this business and lost big time. One guy was almost giving away some really nice trailers. I think he had close to $50K in equipment in each trailer, and was offering them for about $10K. A year later, they were still available. Some of this stuff has gotten so cheap relatively spekaing people don't want the risk of buying used, even if it's "never-been-used used". The complications of selling things go up when the equipment is possibly kitted together with other items that a buyer may not see value in.
Yes, he risks losing this bid to an underbidder by using my math and logic. But he doesn't (IMO) risk losing his ass on the equipment. I think there is enough information here now for him (or others) to decide which is the better bet for his pricing approach.
Again, this is just my opinion, but based on a moderate amount of first-hand experience.