Laser is great for its short start-up and shut-down times. There are some trade-offs though in terms of cost and brightness. I don't think any manufacturer is doing a projector with the combination of brightness, short throw range and Laser lamp that would sit within the budget.
I'm going to concentrate on the outdoor application since that's the primary use.
A lamped projector will need 10-20 seconds start-up and around 20-60 seconds shutdown time typically. Some have an accelerated cool-down function where the fan runs at high speed for 10 seconds. Seems to do the trick.
It's a good idea to be careful when moving a projector during use such as when you're lining it up onscreen, but I've never had a lamp die at that point or when moved after cooling. The only real concern is what happens if power is cut when the projector is on. This is because without the cooling fan running the heat from the now extinguished lamp continues to build up. The answer is (a) be careful around the mains lead and (b) restore power as quickly as possible and let the projector cool.
For outdoor use you'll be up against ambient light, but that never stopped drive-in cinema from working; they just made sensible choices not to try and beat the sun.
I'd go with a gaming projector or similar bright-, short-throw 1080p projector. The Optoma GT1080 is (or has been) available in three different versions. The GT1080e is the £600 version with 3000 ANSI IIRC. There's also the HDR and Darbee versions with slightly different brightness specs and higher prices. 3000 ANSI is pretty pokey for a £600 projector, so you shouldn't have much trouble lighting up a 100" diagonal 16:9 screen area, and you'll get this from just a 1m throw distance. There's a low power/eco mode too which extends the lamp life.
An alternative is the Benq TH671ST. It's also around the £600 mark and has a claimed maximum of 3000 ANSI lumens. 100" is achieved at 1.5m throw.
Lower-cost short-throw projectors have either no zoom at all, or a very limited zoom range. It's a limitation of the optical light path. The slightly longer throw ratio of the Benq allows them to have a small amount of zoom (a smaller image at the same throw distance, or the same size image at a slight longer throw distance). The Optoma has no zoom.
Sound: Unless you're requirements are very basic indeed then I'd always opt for some kind of external sound system. This could be a sound bar, or a set of PC speakers. Whatever it is, you're just looking for something that sounds better than the 3" speaker plonked inside the thing making a bit of fan noise. Most gaming/entertainment projectors will have a sound output on a minimum of a 3.5mm stereo jack.
New or used?
AVForums classifieds section is a fairly safe place to buy used. Sellers there know that there's a lot of folk with decent levels of knowledge, so you won't get exaggerated claims or false advertising. Ebay will offer more choice but from sellers with lower standards. Caveat emptor.
Since both the above are still current models, albeit in revised form, then prices reflect age. Recent units will fetch close to new prices. Older machines will sell for 1/3rd to 1/2 original price depending on age and whether a new lamp is needed. Speaking of lamps, this has been one of the other areas where prices have fallen significantly. The days of a new lamp at a minimum £300-£400 are thankfully long gone. Some of these latest machines have genuine lamps available for under £70.
Copy lamps are available, but more often than not they're a false economy. They don't match the originals for brightness or lamp life. If your new lamp is anything under £150, then stick with a genuine part.
Older/alternative projectors?
There's a bigger choice of standard throw entertainment projectors. Current models such as the Optoma HD143X are bright, and cheaper (£450) but as you know, the throw ratio makes them trickier to accommodate in a limited space. It's the same story with older discontinued models.
