What model is it?
I've got a 45D (actually badged as Omega-View). Officially it's fixed-bellows, single non-extendable monorail. You can unscrew/unglue the bellows and screw in a wide-angle if you want (I did), and easily interchange the monorail with any later extendable versions (I did). The D is nice and light, but very plastic, overtighten a rail clamp and it'll snap (I did). Just push-pull shift and rise, nothing geared.
The E is a bit of a step up, I think it might have geared rise/fall, but still 'officially' fixed bellows.
The G (which I've also got), is a lot more or a beast, more rugged, solid, geared rise and shift, and bellows are interchangeable (mounted on the same size frame as lensboards). But you pay for it in weight. The GII is identical, just new-style knobs. The GX is the same, but with added base-tilt.
The CX is a new version, same rear standard, but bellows taper to smaller 110x110mm lensboards (as on 45A Field). Smaller and lighter, yes, but replacement bellows are harder to come by.
A 45D might only be worth $100-150 shipped anywhere in the US, E maybe slightly more. I paid $300 for my G, definitely a fair price, GX go for a bit more.