I have a Kestral, Brunton and Skymate. Use them all but usually take a Brunton in the zipper pocket in my Eagle stock pack and the Kestral or Skymate in a shirt pocket. Interesting to compare readings with the three models, no difference. I prefer the basic model, don't need some of the more complex weather-station performance. Wind and Temp most used, some guys might like more details. Brunton sometimes has excellent deals on their gear but I just checked and no wind meters right now. You can order direct from Brunton off the net.
Wind meter is a good accessory to have, but it can 't give wind at the target... Good learning tool so you can learn to assess wind using natural indicators. Remember that wind direction is also a key factor.
I have the brunton. I think it cost around 60-70. It also displays date,time, temp, and a couple other little things. Nothing fancy, but works. It helps a little knowing the wind speed, but like Ian said, direction has lots to do with it as well. All in all, its a good tool to have if shooting over 300 yards. Only complaint I have, I sometimes wish that where the wind goes through the tunnel or fan, it was bigger because it seems to have a hard time recording 2-3 mph winds and at 500-800 yards, distances I mostly shoot at, 2-3 mph makes a difference.
I also use a Kestrel, a 3500, and it can't be beat. You can buy cheaper meters but I don't think you'll find a better unit.
Just "google" Kestrel and you will find a lot of different places to buy one.
Just remember though, the wind meter is only going to give you the wind conditions at the point where you are making the shot. In addition to that info, you will still need good optics, and field experience, to read the wind down range up until the first shot and then you have the advantage of seeing the results of that shot. Make any needed adjustments and get another one down range before the conditions change and you will be on the money if you do your part.
I have a Kestrel 4500, but it worked for about a month before I returned it to the factory for repairs. I managed another month with it before it failed again and it's been that way for over a year now. I've emailed Kestrel--at three different addresses one coming off from this website--all I get are ads from them concerning stuff I have no interest in. Now I'm getting aggressive and will get this thing to operate. Which I think means Kestrel will replace this obviously substandard unit.
However, the real reason for this reply is a new piece of equipment that I now use--and recommend instead of any Kestrel--the Windoo. It's Swiss made and you can tell it's well made. More importantly, it works, and all the time. It's half a thumb length and a thumb's diameter. No Bluetooth connection--as yet--but it's instantaneous, accurate, and dependable. I got it off Amazon for $114; it does wind, wind direction, BP, temp, WB, and SP.