For Adults: I highly recommend The Fluke and the Flea, made in Sheffield, Massachusetts by the Magic Fluke company. These can be ordered through their website, The Magic Fluke, and start at $220. I recommend the two larger sizes, Concert (23") or Tenor (25"). I can help you order a Magic Fluke ukulele.
I am also a dealer for Luna (beautiful and affordable) and Journey (ukes and travel guitars) instruments.
Here are four great instruments you can order from INDIE MUSIC (http://www.indiemusicstore.biz/) in Milford (307 Elm St). I have always been a fan of Indie Music, specializing in drums, ukuleles and guitars. Jeff Harrington is the owner and he will make sure that you get what you need!
To order call 603-673-2733 and tell Jeff that you are taking classes with Amy.
Kala Ukulele Soprano size (21") best for ages 4-7. Nylon strings, easy on the fingers. Larger Ukuleles (Concert 23" or Tenor 25"), suitable for adults, start at $59.99. Ukes come in all price ranges, like any instrument!
Lauren ½ Size Guitar: $39.99 For the serious young guitarist. Bigger than a uke, six nylon strings, but still small enough for ages 4 - 8. You might choose this if your child is a real fan of guitars already. (nylon case $9.99*)
Dean ¾ size Acoustic: $69.99 with nylon case. Best for children ages 8 and up, in my opinion. However, it comes with steel strings which are harder to learn on than nylon. If you are looking for a guitar for a child this age, call Jeff and see if he has any half or ¾ size nylon string guitars to recommend. I like the Dean because they look sturdy and sound nice. Some kids like the steel string sound. Choose Color: Natural, Black, Blue, Pink.
Accessories String Swing $12, hook that attaches to wall so you can see your uke or guitar every day, maybe even take it down and play it! Straps are very handy also, Indie Music in Milford has a large selection of straps, and can install a strap button at the end of your uke or guitar if there is not one already.