EDIT: I should have put this first.
Provided your kid's instructor is a real oboe player, you should ask him, first -- and say, "Well, I've heard about these horns from $folks_here." You never know: your kid's instructor might have an oboe just sitting around ....
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Loree or Marigaux.
(They're high end. Expensive.)
Check out
http://oboes.us. The gentleman that runs the website is a former president of the National Hecklephone Society (for all the, oh, 100 people that have Hecklephones), but he does have some used/consignment oboes.
1. If your son can play oboe passably well, he'll always have a job.
2. Remember: you're going to be talking about some serious cash. While the extreme high-end oboes are actually less expensive than the extreme high-end of all other woodwinds, even student model new oboes start at over $1000.
Fox 330: $3200
Selmer 101: $3200
Bulgheroni: $2500
Marigaux Pro: $9000
I attempted to teach myself how to play oboe on either a Signet or Bundy. Don't remember which. It lasted for a couple weeks ....
Merlin and Bpimentel are very correct: oboes have a lot of additional keywork and some have different keywork systems. I also caution with vintage instruments: double-reeds have a tendency to be in odd tuning (purposely), moreso than just about any other instrument. You want modern pitch, A=440hz or A=442hz (European orchestral).
I'd get the Fox, just based on the fact that the double-reed players I've known have always used Fox instruments.