Don't waste your money on the one from Spray n Grow. I love their other garden products but I tried the sprayer twice and both times it broke in the first season. Not very sturdy.

get an Atomist and a bunch of extension cords. Great sprayer.

Spot Shot sprayer from Rosemania. I've had one for 10 years (or however long they've been selling it). You can get the batteries pretty cheap at Home Depot and other places (like $25 instead of $45) and you can even buy a 12V motorcycle charger at Walmart (much better and safer than the un-controlled walwart that comes with the Spot Shot).

I make sure to completely rinse the jugs when finished and then run an entire jug of clean water through the spray nozzle before putting it up each time. That's the only maintenance I've ever done on it besides replacing the battery.

During the peak season, I spray 10 - 12 gallons at a time, which takes two jugs, at least. No problems whatsoever. It even sprays 12 gallons of Bayer + Pentathlon (manzate powder) on a single charge and that stuff is thick! It's the greatest thing on two wheels for roses. :-)

I use a 12-gallon Mantis Spray Mate, and I love it!! It was recommended by a friend, and I found at that time that it was no longer available. Grrrr. It was serendipity one morning as I was googling one last time ... found one on CL in Maine (I'm in Virginia) Contacted the seller, who was happy to sell it and ship it to me. (no interest at all in it locally) Did my entire garden on Saturday morning, took only 2 hours (including mixing the fungicide and cleaning the sprayer afterward.)

Here is a link that might be useful: Photos of the sprayer in this blog post.

I have been using this Fimco sprayer from Rosemania now for a few years. I can do all my roses mixing just once, and the wheels make it very easy to cart around.

Here is a link that might be useful: Battery operated sprayer

Thanks to all of you for your feedback. SpotShot is a bit expensive for me; I will have to do some more research before I come to a conclusion. Atomist probably is not a choice because of health hazard.