Your requirement for a $300, light weight, big fish reel is not easy to accomplish. Here are a few to consider.
The Nautilus Feather Weight+ is a good choice but you will have to use Gel Spun backing to use a 9wt line. It is not big enough for a 10wt. Price is $350.
Nautilus Feather Weight+
The Orvis Battenkill Big Game will hold a 9wt line and plenty of backing. Price is $250.
Orvis Battenkill Large Arbor Big Game Reel
The Galvan T10 is a very good reel but is more money. Price $450
The Teton 8-10 is a very good reel for the price. Teton is closed right now but they are looking for a buyer. If you call the factory you might get a good deal. Other dealers still have them in stock. The problem is there may not be any factory support.