If you are looking for used instruments on the second hand market, there are a lot of options out there. It would be best if you are able to test the instrument out yourself and know what to look for when shopping the used market. Here are a few tips of what to look for and a few brands to keep an eye out for.
Looking over for issues:
-Look for obvious issues like dents/cracks/damage that would affect the playing condition
-Trumpets/baritones: make sure that the slides will all pull out (not stuck) and that the valves operate smoothly
-Flutes/Clarinets/Alto Saxophones: make sure that keys move smoothly and that the pads are all intact, in good shape and close completely over the openings.
-String Instruments: Check for cracks in the body of the instrument. Make sure the instrument is the right size for your child. If not sure what size your child needs, check out this link:
https://thevault.musicarts.com/sizing-your-string-instrumemt/
Instrument Brands to look for:
This is in no way an exhaustive list. These are just some suggestions on brands that make quality student model instruments. Many of these brands are used as rentals/sold in local stores and may be more available on the used market.
Flute: Geimenhardt, Armstrong, Yamaha, Selmer
Clarinet: Bundy, Vito, Yamaha, Selmer
Alto: Bundy, Conn-Selmer, Yamaha
Trumpet/Trombone/Baritone: Bach, Yamaha, Eastman, Conn-Selmer
String Instruments: Eastman, Strobel, Leon Albert, Andrew Schroetter, Glaesel