Hi!
Are you planning to take further grades? If so, I think that an intermediate clarinet would be good for you, and could take you to grade 8 if needs be! Here are some intermediate clarinets I would suggest:
Buffet E11
Buffet E13
Yamaha 450
Yamaha 650 (my teacher has one of these!)
Boosey & Hawkes Imperial 926 (This is actually a pro clarinet which I have! They can only be bought second hand and old, but they have the deepest, richest tone you could imagine! This is a British make that was bought out by Buffet about 20 years ago, but a B & H clarinet in good condition is just wonderful! Mine was £500, i'm not sure what that is in dollars!)
B&H Edgeware ( not as good)
I've also heard that Selmer make good clarinets. I have a friend who has a professional Selmer that plays like a dream! I don't know about the others.
Leblanc is also a good French make that I don't know much of! I've only heard that they're good!
There are many to avoid, too!
Jupiter
Always go with well known brands! Do not buy a good
looking clarinet off the Internet if you haven't heard of them often. ALWAYS try your instrument before you buy it!
I hope you found this helpful! Good Luck!