In my experience, JBLs have evoked a kind of hatred that hasn't been equalled in the spearo community. They aren't BAD guns, but there's nothing like the mention of a JBL to bring out the trash talk.
In days past, I've used the JBL Carbine/Explorer 22/38-Special, AB Billers in several sizes, have inspected Spearfishing Specialties Seahornets in detail, and have used many euro brands, so I feel confident that I can give you some good advice.
The big question is scuba or freedive?
Scuba: For that price range, you would probably be better off with an AB Biller or SS Sea Hornet. These guns are a similar style, but have a much more reliable trigger mechanism and sligtly better ballance in my opinion. The SS would be a step up from the Biller in that the handle is more comfortable and they have a few upgraded features like heavy mono rigging.
Freedive: There are a number of Euro-style guns like Omer, Rob Allen, Rabitech, Pelaj, Cressi, Sporasub, etc. for the same price. These are good quality guns and have much better ergonomics compared to the "scuba guns" like the JBL/Biller/SS.
The best option is to go diving with some peers and try their guns to see if you like them.
Good Luck,
Kolt