Where does one purchase a wicket? I know I could make one out of yardsticks but would prefer a device that's a bit more precise. Thanks

www.onofrio.com
If you can afford them, On the homepage.
JBwholesale used to.As that is where I bought mine.

http://www.ezwicket.com/

$85.00 + shipping for labrador height

I think I may invest in one. Had the wicket called on my "petite" girl earlier this year, so I'd like to be able to get an official height on her again now that she looks like she may have squeaked out another 1/2 inch.

An official AKC wicket is different from an obedience wicket.

The AKC wicket is made from very heavy surgical steel.
When it is placed on the highest point of the shoulder, the two legs of the wicket can hit the floor, stand on the floor with a gap between the wicket and the dog or dangle above the floor. The weight of the wicket is an important factor in the correct measurement. Unless they have changed the rules, an individual cannot buy an AKC wicket - only a club or superintendent.

An obedience wicket is not usually heavy or accurate.
If you are looking for an approximate measurement then the obedience wicket is OK. If you want to know if you dog will measure in or out of standard, you need to have it measured with the AKC wicket.

JSLRC bought an AKC wicket years ago when the height DQ was added to the standard. We brought it to our match shows and other events and asked for a $1 donation for each dog wicketed to help defray the cost. Members are allowed to borrow it so they can measure their dogs in the privacy of their own homes.