I'm not an expert, but I own two different spearguns, and can give you some info on the Riffe, as I own one.
First, the midhandle is not what you probably want, even though you may THINK you do. You DO NOT want to fire a speargun like a regular firearm; you typically shoot while horizontal in the water, while you shoot a gun while vertical (most of the time anyway); the key difference is that you do not SHOULDER a speargun when firing.
Rather, a speargun is fired with your arm LOCKED and extended and, in many if not most cases, with the second hand on the butt of the gun as a steadying and aiming aid. You have to "be the shaft"; its not really aimed like a firearm. The key is that you don't want to "eat" the gun fro the recoil; it can happen, and if it does it will shatter your mask or knock it off (bad at 100'!)
I own a Riffe C3x. You can get that gun for less than your budget, and it will "reach out and touch things" very well. Riffe's guns are also slower to load though than many others, which, if you shoot a lot of fish on a given dive, can be a big deal. That's a 50-something inch gun. Its a BEAST to hip-load; you either learn to chest-load in a big hurry, or you will have problems unless you're 6'2 or similar, especially if you have to reload a lot (e.g. lots of fish being shot OR you miss frequently!)
I also own a JBL "sawed off" Magnum, which is a roughly 4' gun. This gun is MUCH faster to reload, but it does not have the power of the Riffe.
To a large extent, what you put in (in effort loading the bands) is what you get out (in spearing power.)
Before spending gobs of money on a very non-returnable purchase, instead find some friends who have a "backup" gun and see if they'll let you try whatever you are thinking of. You'll learn a lot - what you like and don't, and what you want to buy.
For me the JBL is a great "wreck" gun, as its fast to maneuver around the wrecks and is easily and quickly loaded. It lacks the power of the Riffe though. But the Riffe, while much more powerful, is slow on the reload and is quite a bit harder to swing around on target underwater.
I use both for different occasions; if I am intending to shoot larger fish I take the Riffe; for smaller bumming around the JBL will bag more in a given amount of time.
As with most things, there is no free lunch.