Why not make them yourself. It requires a grand total of two power tools and a cordless drill. And it is a really fun and satisfying project.
You need a hole saw for the cordless drill, a couple of drill bits and one of those cheap grindstones that fit into the drill chuck (they sell them ina box of different shapes and colours by the counter of the hardware store) and a bolt that you are going to grind into the seating tool for perfectly rebating and countersinking all of the bolt holes in your grab rails.
A router (a cheap one costs about $40, but it is usefull owning a decent one that will last you for years) and a large rounding bit (it is one of the bits that comes standard with most cheap routers you buy, and while it is not of great quality, it will do this job with ease)
A jigsaw or saws-all and wood-cutting blade.
And like the bought ones, you will need: A few sheets of sand paper, wooden plugs or filler for the bolt holes and varnish or oil to finish off
That's it. And the nice thing is that you make these in matched pairs, you automatically get two rails everytime.
I did a "how to" article on this for our local sailing site and club newsletter. I can dig it out for you if you are interested.