I can't comment on the inflatable aspects, but good friends of ours have water spritzer hoses set up on motion detectors to control the deer and have had excellent luck. I like the inflatable idea better - you don't have to remember to turn the motion detectors off if you need to run across the yard! I guess the question is if the deer are actually scared off by the inflatable.

If you decide to go for the fence, there is deer fencing that is made of black netting and so disappears relatively well against a backdrop of plants, or you can set up an attractive fence such as a picket fence with several strands of wire above it or past it. Deer have a harder time with a fence that's difficult to see or doesn't give them a clear landing area.

There are also sprays such as Liquid Fence. The one time I had deer issues, I sprayed with a mixture of Wiltpruf and a deer repellant. The Wiltpruf is an antidesiccant, but it also prevents the deer repellant from washing off when it rains. There are recipes for homemade deer repellants, usually combining in some form old eggs, blood meal (sold as a fertilizer at farm and garden stores), garlic, hot peppers, etc. (see link below)

From what I understand about deer behavior, keeping them thinking that there are more appealing foods and less scary areas to eat than in your garden are a big part of keeping them from creating too much damage. Most reading I did during the one time I had deer issues in this garden said rotate the things that deer don't like. So move around physically scary things like motion-activated sprinklers, radios, and inflatables, and use more than one recipe for your sprays that make plants taste unpalatable. They seem to be creatures of habit, so always having something unexpected and aversive keeps your garden less appealing. Once they are in the habit of considering your garden a good long-term food source it may be more difficult to get rid of them. So start now and continue consistently next spring and summer for best results to prevent them from viewing your garden as a comfortable spot.

There are many discussions of ways to deal with deer on the Plants for Difficult Places, such as suggestions on repellents and fencing or plants that seem less palatable to deer.
http://forums.gardenweb.com/forums/difficult/

Good luck! You have my sympathy.

Here is a link that might be useful: homemade deer repellents

NHbabs makes a good point about more appealing food elsewhere. When we first moved here, deer fed on some of my hostas so I sprayed with the deer repellant which seemed to work. But what has probably also worked is that a field next to our property has been rejuvenated by a local farmer who plants cow corn and winter rye. Apparently these are much tastier. Occasionally the deer take a shortcut thru a corner of our property but don't seem to be bothering the garden. Good luck since 2008 and I hope it continues. Is it possible deer have better food nearby so they don't bother your garden?

Well, now that I'm not spending much time in the garden, the deer might have decided it's been abandoned and time for a free for all. The last cabbage was half eaten. The parsnips and chard have been browsed. I'm sorry to lose the chard but I have more greens in the high tunnel and I wasn't sure what I was going to do with the last cabbage (others went to church supper cole slaw). This is a very small loss but a reminder that next year I should probably go back to spraying repellant around the perimeter of the beds.

Deer have been eating my parsley, but haven't touched the kale right next to it. I think I will need to encourage them to change their habits next spring so that they stay out of the veggies. This fall is the first time they have bothered the veggie garden in more than 10 years.

I have had a large and serious deer problem for about 12 years. Fencing the whole property is not possible and has drawbacks--expense, maintenance etc. Liquid Fence has been a lifesaver tho it is not cheap and must be renewed every month or so. I wish I had known about it when the vermin first appeared. I lost many shrubs trying other methods.